Circadian rhythm sleep disorders: part I, basic principles, shift work and jet lag disorders. An American Academy of Sleep Medicine review

Associations of Rest-Activity Rhythm Disturbances With Stroke Risk and Poststroke Adverse Outcomes

BACKGROUND

Many disease processes are influenced by circadian clocks and display ~24-hour rhythms. Whether disruptions to these rhythms increase stroke risk is unclear. We evaluated the association between 24-hour rest-activity rhythms, stroke risk, and major poststroke adverse outcomes.

METHODS AND RESULTS

We examined ~100 000 participants from the UK Biobank (aged 44-79 years; ~57% women) assessed with actigraphy (6-7 days) and 5-year median follow-up. We derived (1) most active 10-hour activity counts across the 24-hour cycle and the timing of its midpoint timing; (2) the least active 5-hour count and its midpoint; (3) relative amplitude; (4) interdaily stability; and (5) intradaily variability, for stability and fragmentation of the rhythm. Cox proportional hazard models were constructed for time to (1) incident stroke (n=1652) and (2) poststroke adverse outcomes (dementia, depression, disability, or death). Suppressed relative amplitude (lowest quartile [quartile 1] versus the top quartile [quartile 4]) was associated with stroke risk (hazard ratio [HR], 1.61 [95% CI, 1.35-1.92]; P<0.001) after adjusting for demographics. Later most active 10-hour activity count midpoint timing (14:00-15:26; HR, 1.26 [95% CI, 1.07-1.49]; P=0.007) also had higher stroke risk than earlier (12:17-13:10) participants. A fragmented rhythm (intradaily variability) was also associated with higher stroke risk (quartile 4 versus quartile 1; HR, 1.26 [95% CI, 1.06-1.49]; P=0.008). Suppressed relative amplitude was associated with risk for poststroke adverse outcomes (quartile 1 versus quartile 4; HR, 2.02 [95% CI, 1.46-2.48]; P<0.001). All associations were independent of age, sex, race, obesity, sleep disorders, cardiovascular diseases or risks, and other comorbidity burdens.

CONCLUSIONS

Suppressed 24-hour rest-activity rhythm may be a risk factor for stroke and an early indicator of major poststroke adverse outcomes.

Circadian disruptions and their role in the development of hypertension

Circadian fluctuations in physiological setpoints are determined by the suprachiasmatic nucleus (SCN) which exerts control over many target structures within and beyond the hypothalamus via projections. The SCN, or central pacemaker, orchestrates synchrony between the external environment and the internal circadian mechanism. The resulting cycles in hormone levels and autonomic nervous system (ANS) activity provide precise messages to specific organs, adjusting, for example, their sensitivity to approaching hormones or metabolites. The SCN responds to both photic (light) and non-photic input. Circadian patterns are found in both heart rate and blood pressure, which are linked to daily variations in activity and autonomic nervous system activity. Variations in blood pressure are of great interest as several cardiovascular diseases such as stroke, arrhythmias, and hypertension are linked to circadian rhythm dysregulation. The disruption of normal day-night cycles, such as in shift work, social jetlag, or eating outside of normal hours leads to desynchronization of the central and peripheral clocks. This desynchronization leads to disorganization of the cellular processes that are normally driven by the interactions of the SCN and photic input. Here, we review autonomic system function and dysfunction due to regulation and interaction between different cardiorespiratory brain centers and the SCN, as well as social, lifestyle, and external factors that may impact the circadian control of blood pressure.

Pattern of sleep disorders among children with autism spectrum disorder

BACKGROUND

Sleep disorders (SDs) are among many co-morbid medical conditions that affect children with autism spectrum disorder (ASD). Raising awareness and improving the standard of care for children diagnosed with ASD may result from identifying SDs among them. This study aims to evaluate patterns of SDs among Sudanese children diagnosed with ASD.

METHOD

Using the Childhood Sleep Habit Questionnaire (CSHQ) to gather data on sleep disorders and SPSS version 26.0 for data analysis, a descriptive cross-sectional study was carried out in the five main autistic centres in Khartoum state covering all registered patients with ASD between April and June 2022. Ninety-two children diagnosed with ASD were enrolled in this study after the purpose of the research was explained and consent was obtained from their guardians. A p-value < 0.05 was considered to indicate statistical significance.

RESULTS

The mean age was 6.90 (± 2.6) years with a boys-to-girls ratio of 2.17:1. The prevalence of SDs (at least one sleep condition almost daily) was 95.65%. Sleep onset 71 (77.2%), limit setting 32 (32.6%), resistant onset to sleep 48 (52.2%), and combined 52 (56.5%) insomnia affected the majority of children. Additionally, there were significant associations between sex and Limit-setting insomnia, advanced sleep phase disorder, and narcolepsy type 2 (P values = 0.033, 0.009, and 0.037, respectively). Additionally, there was a significant association between age and sleep-related breathing disorders-snoring (p value = 0.031).

CONCLUSION

The frequency of SDs is significant among children diagnosed with ASD from Sudan, and certain SDs are associated with age and sex. Subsequent studies are required to develop national guidelines for the prevalence, presentation, screening, and treatment of SDs in children diagnosed with ASD.

Identifying Links Between Productivity and Biobehavioral Rhythms Modeled From Multimodal Sensor Streams: Exploratory Quantitative Study

BACKGROUND

Biobehavioral rhythms are biological, behavioral, and psychosocial processes with repeating cycles. Abnormal rhythms have been linked to various health issues, such as sleep disorders, obesity, and depression.

OBJECTIVE

This study aims to identify links between productivity and biobehavioral rhythms modeled from passively collected mobile data streams.

METHODS

In this study, we used a multimodal mobile sensing data set consisting of data collected from smartphones and Fitbits worn by 188 college students over a continuous period of 16 weeks. The participants reported their self-evaluated daily productivity score (ranging from 0 to 4) during weeks 1, 6, and 15. To analyze the data, we modeled cyclic human behavior patterns based on multimodal mobile sensing data gathered during weeks 1, 6, 15, and the adjacent weeks. Our methodology resulted in the creation of a rhythm model for each sensor feature. Additionally, we developed a correlation-based approach to identify connections between rhythm stability and high or low productivity levels.

RESULTS

Differences exist in the biobehavioral rhythms of high- and low-productivity students, with those demonstrating greater rhythm stability also exhibiting higher productivity levels. Notably, a negative correlation (C=-0.16) was observed between productivity and the SE of the phase for the 24-hour period during week 1, with a higher SE indicative of lower rhythm stability.

CONCLUSIONS

Modeling biobehavioral rhythms has the potential to quantify and forecast productivity. The findings have implications for building novel cyber-human systems that align with human beings' biobehavioral rhythms to improve health, well-being, and work performance.

Association of sleep traits with male fertility: a two-sample Mendelian randomization study

Background: Previous observational studies have investigated the association between sleep-related traits and male fertility; however, conclusive evidence of a causal connection is lacking. This study aimed to explore the causal relationship between sleep and male fertility using Mendelian randomisation. Methods: Eight sleep-related traits (chronotype, sleep duration, insomnia, snoring, dozing, daytime nap, oversleeping, and undersleeping) and three descriptors representing male fertility (male infertility, abnormal sperm, and bioavailable testosterone levels) were selected from published Genome-Wide Association Studies. The causal relationship between sleep-related traits and male fertility was evaluated using multiple methods, including inverse variance weighting (IVW), weighted median, Mendelian randomisation-Egger, weighted model, and simple model through two-sample Mendelian randomisation analysis. Mendelian randomisation-Egger regression was used to assess pleiotropy, Cochrane's Q test was employed to detect heterogeneity, and a leave-one-out sensitivity analysis was conducted. Results: Genetically-predicted chronotype (IVW,OR = 1.07; 95%CL = 1.04-1.12; p = 0.0002) was suggestively associated with bioavailable testosterone levels. However, using the IVW method, we found no evidence of a causal association between other sleep traits and male fertility. Conclusion: This study found that chronotype affects testosterone secretion levels. However, further studies are needed to explain this mechanism.

Optimal phase-based control of strongly perturbed limit cycle oscillators using phase reduction techniques

Phase reduction is a well-established technique for analysis and control of weakly perturbed limit cycle oscillators. However, its accuracy is diminished in a strongly perturbed setting where information about the amplitude dynamics must also be considered. In this paper, we consider phase-based control of general limit cycle oscillators in both weakly and strongly perturbed regimes. For use at the strongly perturbed end of the continuum, we propose a strategy for optimal phase control of general limit cycle oscillators that uses an adaptive phase-amplitude reduced order model in conjunction with dynamic programming. This strategy can accommodate large magnitude inputs at the expense of requiring additional dimensions in the reduced order equations, thereby increasing the computational complexity. We apply this strategy to two biologically motivated prototype problems and provide direct comparisons to two related phase-based control algorithms. In situations where other commonly used strategies fail due to the application of large magnitude inputs, the adaptive phase-amplitude reduction provides a viable reduced order model while still yielding a computationally tractable control problem. These results highlight the need for discernment in reduced order model selection for limit cycle oscillators to balance the trade-off between accuracy and dimensionality.

Rosemary (Rosmarinus officinalis L.) hydrosol based on serotonergic synapse for insomnia

ETHNOPHARMACOLOGICAL RELEVANCE

Rosemary (Rosmarinus officinalis L.) has been widely used as a traditional remedy for insomnia, depression and anxiety in China and Western countries. Modern pharmacological studies have shown that rosemary has important applications in neurological disorders. However, the mechanism of action of rosemary hydrosol in the treatment of insomnia is not known.

AIMS OF THE STUDY

Insomnia is closely linked to anxiety and depression, and its pathogenesis is related to biology, psychology, and sociology. Rosemary is a natural plant that has been used to treat insomnia and depression and has good biological activity, but its material basis and mechanism for the treatment of insomnia are not clear. Here, we report on the role of aqueous extracts of rosemary in the treatment of insomnia.

MATERIALS AND METHODS

The study was based on network pharmacology, using a combination of RNA-sequencing, "quantity-effect" weighting coefficients, and pharmacodynamic experiments. DL-4-chlorophenylalanine (PCPA) was intraperitoneally injected into SD rats to replicate the insomnia model with a blank, model, diazepam, and rosemary hydrosol low-, medium-, and high-dose groups were set up for the experiment. The key pathways in the treatment of insomnia with rosemary hydrosol were analyzed by molecular docking, open field assay, ELISA, western-Blot, Rt-PCR, and immunohistochemical assay.

RESULTS

Rosemary hydrosol was analyzed by GC-MS to identify 19 components. 1579 differential genes were obtained by RNA-Seq analysis, 533 targets for rosemary hydrosol and 2705 targets for insomnia, and 29 key targets were obtained by intersection. The KEGG results were ranked by "quantity-effect" weighting coefficients, resulting in serotonergic synapse was the key pathway for the treatment of insomnia with rosemary hydrosol. Molecular docking results showed that 1,7,7-trimethylbicyclo[2.2.1] heptan-2-one, 3-methyl-4-isopropylphenol, caryophyllene, and citronellol of rosemary hydrosol acted synergistically to achieve a therapeutic effect on insomnia. Caryophyllene acts on the HTR1A target by upregulating 5-HT1AR, leading to increased 5-HT release, and upregulation of ADCY5, cAMP, PKA and GABAA at serotonergic synapses; citronellol upregulated ADCY5 and 1,7,7-trimethylbicyclo[2.2.1] heptan-2-one, and 3-methyl-4-isopropylphenol up-regulated GABAA to improve insomnia symptoms. In open-field experiments, ELISA kits (5-HT, GABA, and DA), Western-blotting, Rt-PCR and immunohistochemical assay experiments, insomnia rats in the low-, medium- and high-dose groups of rosemary hydrosol showed different degrees of improvement compared with the model group.

CONCLUSIONS

It was shown that rosemary hydrosol may exert its therapeutic effects on insomnia through serotonergic synapses by combining RNA-Seq, "quantity-effect" weighting coefficients network pharmacology and pharmacodynamic experiments. We have provided a preliminary theoretical study for the development of rosemary hydrosol additive into a beverage for the treatment of insomnia, but it needs to be studied in depth. This study was conducted in rats and the results have limitations and may not apply to humans.

Insomnia and related mental health conditions: Essential neurobiological underpinnings towards reduced polypharmacy utilization rates

Insomnia represents a significant public health burden, with a 10% prevalence in the general population. Reduced sleep affects social and working functioning, productivity, and patient's quality of life, leading to a total of $100 billion per year in direct and indirect healthcare costs. Primary insomnia is unrelated to any other mental or medical illness; secondary insomnia co-occurs with other underlying medical, iatrogenic, or mental conditions. Epidemiological studies found a 40-50% comorbidity prevalence between insomnia and psychiatric disorders, suggesting a high relevance of mental health in insomniacs. Sleep disturbances also worsen the outcomes of several psychiatric disorders, leading to more severe psychopathology and incomplete remission, plausibly contributing to treatment-resistant conditions. Insomnia and psychiatric disorder coexistence can lead to polypharmacy, namely, the concurrent use of two or more medications in the same patient, regardless of their purpose or rationale. Polypharmacy increases the risk of using unnecessary drugs, the likelihood of drug interactions and adverse events, and reduces the patient's compliance due to regimen complexity. The workup of insomnia must consider the patient's sleep habits and inquire about any medical and mental concurrent conditions that must be handled to allow insomnia to be remitted adequately. Monotherapy or limited polypharmacy should be preferred, especially in case of multiple comorbidities, promoting multipurpose molecules with sedative properties and with bedtime administration. Also, non-pharmacological interventions for insomnia, such as sleep hygiene, relaxation training and Cognitive Behavioral Therapy may be useful in secondary insomnia to confront behaviors and thoughts contributing to insomnia and help optimizing the pharmacotherapy. However, insomnia therapy should always be patient-tailored, considering drug indications, contraindications, and pharmacokinetics, besides insomnia phenotype, clinical picture, patient preferences, and side effect profile.

Microglial Regulation of Sleep and Wakefulness

Sleep serves a multitude of roles in brain maturation and function. Although the neural networks involved in sleep regulation have been extensively characterized, it is increasingly recognized that neurons are not the sole conductor orchestrating the rhythmic cycle of sleep and wakefulness. In the central nervous system, microglia have emerged as an important player in sleep regulation. Within the last two decades, microglia have gained substantial attention for carrying out numerous nonimmune tasks that are crucial for brain development and function by co-opting similar mechanisms used in their conventional immune functions. Here, we highlight the importance of microglia in sleep regulation with recent findings reporting an arrhythmic sleep/wake cycle in the absence of microglia. Although the underlying mechanisms for such regulation are still being uncovered, it is likely that microglial contributions to the rhythmic control of the sleep/wake cycle come from their influence on synaptic strength and neuronal activity. We review the current literature to provide speculative signaling pathways and suggest key questions for future research. Advancing our knowledge of the mechanistic contribution of microglia to sleep regulation will not only further our insight into this critical biological process but also be instrumental in providing novel therapeutic strategies for sleep disorders.

Early time-restricted eating advances sleep in late sleepers: a pilot randomized controlled trial

STUDY OBJECTIVES

This study evaluated the effects of early time-restricted eating (eTRE) on shifting the timing of sleep among late sleepers. Primary outcomes included actigraphy- and sleep diary-derived sleep onset, midsleep phase, and wake time with total sleep time as a secondary outcome.

METHODS

Fifteen healthy adults with habitual late sleep timing were randomized to receive either eTRE or sleep and nutrition hygiene (control) via a single 30-minute synchronous video session. Participants completed an initial 1-week baseline phase followed by a 2-week intervention phase. Measures included continuous sleep monitoring and sleep and nutrition diaries.

RESULTS

Linear mixed-effects modeling demonstrated that eTRE significantly advanced sleep timing compared with controls. Self-reported sleep onset (56.1 [95% confidence interval: 20.5, 91.7] minutes), midpoint (19.5 [7.2, 31.9] minutes), and offset (42.2 [2.9, 81.5] minutes) each moved earlier in eTRE as compared with controls. Similarly, objectively determined sleep onset (66.5 [29.6, 103.4] minutes), midpoint (21.9 [9.1, 34.7] minutes), and offset (39.3 [1.3, 77.3] minutes) each moved earlier in eTRE as compared with controls. Total sleep time showed a nonsignificant increase in the eTRE group as compared with controls.

CONCLUSIONS

Late sleepers who were instructed in a single session about eTRE significantly advanced their sleep timing, especially sleep onset. eTRE shows potential as a clinical strategy for advancing sleep timing in late sleepers.

CLINICAL TRIAL REGISTRATION

Registry: Chinese Clinical Trial Registry; Name: FAST Asleep: It's All About Timing; URL: https://www.chictr.org.cn/showproj.html?proj=122504; Identifier: ChiCTR2100043691.

CITATION

Blum DJ, Hernandez B, Zeitzer JM. Early time-restricted eating advances sleep in late sleepers: a pilot randomized controlled trial. J Clin Sleep Med. 2023;19(12):2097-2106.

The prevalence of temporomandibular disorder and temporomandibular morphology among diverse chronotype profiles

This study investigates the influence of chronotype on the prevalence of temporomandibular joint disorders (TMD) and the morphology of temporomandibular joint (TMJ). According to the Morningness-Eveningness Questionnaire-Self-Assessment, the participants were divided into morning group (n = 30), intermediate group (n = 83), and evening group (n = 30). Thirty participants were randomly selected from the intermediate group for subsequent examination and measurements. The morphology of TMJs was investigated using questionnaire and clinical examination form in Diagnostic Criteria for Temporomandibular Disorder. Meanwhile, the morphological results of TMJs were measured from cone-beam computed tomography images. The prevalence rate of TMD in the morning group (23%) was significantly lower than that in the intermediate group (56.7%), while there was no difference between the evening (53.4%) and intermediate groups. As to morphological measurements, there was no significant difference among three groups in mediolateral width of condylar process, anteroposterior width of condylar process, radius of condyle, medial joint space, lateral joint space, condylar stress angle, horizontal condylar inclination, width of glenoid fossa, depth of glenoid fossa, and posterior joint space, while there was a significant difference in horizontal condylar angle (p = 0.00490), articular eminence inclination (p < .0001), anterior joint space (p = 0.0163), and superior joint space (p = 0.0004). The morphology of TMJ in the morning group was better than that in the evening and intermediate groups. An association was found between TMD prevalence, temporomandibular morphology, and chronotype.

The subjective amplitude of the diurnal rhythm matters - Chronobiological insights for neuroimaging studies

Multiple aspects of human psychophysiology, including mood and cognition, are subjected to diurnal rhythms. While the previous magnetic resonance imaging (MRI) studies have focused solely on the morningness-eveningness (ME) preference dichotomy, i.e. the circadian phase, the second key dimension of the diurnal rhythms, i.e. the strength of these preferences (amplitude; AM), has been completely overlooked. Uncovering the neural correlates of AM is especially important considering its link with negative emotionality. Structural T1-weighted neuroimaging data from 79 early (EC) and 74 late (LC) chronotypes were analysed to compare grey matter (GM) volume and cortical thickness. The study aimed to elucidate whether the subjective AM and its interaction with ME was a significant predictor of individual brain structure. Both GM volume and cortical thickness of the left primary visual cortex was negatively correlated with AM scores across the entire sample. Furthermore, EC and LC differed in their association between AM scores and the GM volume in the right middle temporal gyrus, with the positive and negative correlations reported respectively in the two groups. The current study underlines the importance of the visual system in circadian rhythmicity and provides possible neural correlates for AM-related differences in negative affect processing. Furthermore, the presence of the opposite correlations between brain anatomy and AM in the two groups suggests that the behavioural and neuronal chronotype differences might become more pronounced in individuals with extreme diurnal differences in mood and cognition, highlighting the necessity to additionally account for AM in neuroimaging studies.

CIRCUST: A novel methodology for temporal order reconstruction of molecular rhythms; validation and application towards a daily rhythm gene expression atlas in humans

The circadian system drives near-24-h oscillations in behaviors and biological processes. The underlying core molecular clock regulates the expression of other genes, and it has been shown that the expression of more than 50 percent of genes in mammals displays 24-h rhythmic patterns, with the specific genes that cycle varying from one tissue to another. Determining rhythmic gene expression patterns in human tissues sampled as single timepoints has several challenges, including the reconstruction of temporal order of highly noisy data. Previous methodologies have attempted to address these challenges in one or a small number of tissues for which rhythmic gene evolutionary conservation is assumed to be preserved. Here we introduce CIRCUST, a novel CIRCular-robUST methodology for analyzing molecular rhythms, that relies on circular statistics, is robust against noise, and requires fewer assumptions than existing methodologies. Next, we validated the method against four controlled experiments in which sampling times were known, and finally, CIRCUST was applied to 34 tissues from the Genotype-Tissue Expression (GTEx) dataset with the aim towards building a comprehensive daily rhythm gene expression atlas in humans. The validation and application shown here indicate that CIRCUST provides a flexible framework to formulate and solve the issues related to the analysis of molecular rhythms in human tissues. CIRCUST methodology is publicly available at https://github.com/yolandalago/CIRCUST/.

A daily examination of executive functioning and chronotype in bedtime procrastination

STUDY OBJECTIVES

Bedtime procrastination, or delays in bedtime not attributable to external obligations, is a behavioral tendency that undermines sleep and is conceptualized as a consequence of poor self-regulation. Prior studies investigating the mechanistic role of self-regulation in bedtime procrastination relied on cross-sectional methods and self-reported self-regulation. The present study examined the association between bedtime procrastination and both objective and self-reported executive functioning (EF) as indices of self-regulation, as well as the moderating role of chronotype, using methods that examined these associations at the daily level.

METHODS

A total of 273 young adult participants (78% female; Mage = 24.4) completed daily measures of objective EF (i.e., Stroop task), self-reported EF (i.e., self-reported cognitive, behavioral, and emotional regulation difficulties), and bedtime procrastination over 14 days, in addition to measures of chronotype. Multilevel models were constructed to examine the associations between bedtime procrastination and EF, as well as EF-chronotype interactions.

RESULTS

Poorer daily objective EF and self-reported behavioral regulation were associated with greater same-night bedtime procrastination. Additionally, poorer subjective cognitive and emotional regulation were associated with greater average bedtime procrastination across 14 days. Later chronotypes reported greater bedtime procrastination than early chronotypes.

CONCLUSIONS

The present study provides support for the association between EF and bedtime procrastination, but finds no evidence for the moderating role of chronotype in this association. Results suggest that some EF processes may be more relevant to bedtime procrastination than others. Current findings have implications for assessment and intervention for this consequential sleep-relevant behavioral tendency.

Associations of rest-activity rhythm disturbances with stroke risk and post-stroke adverse outcomes

Background

Almost all biological and disease processes are influenced by circadian clocks and display ∼24-hour rhythms. Disruption of these rhythms may be an important novel risk factor for stroke. We evaluated the association between 24-h rest-activity rhythm measures, stroke risk, and major post-stroke adverse outcomes.

Methods

In this cohort study, we examined ∼100,000 participants in the UK Biobank (44-79 years old; ∼57% females) who underwent an actigraphy (6-7 days) and 5-year median follow-up. We derived: (1) most active 10 hours activity counts ( M10 ) across the 24-h cycle and the timing of its midpoint ( M10 midpoint ); (2) the least active 5 hours counts ( L5 ) and its midpoint timing ( L5 midpoint ); (3) relative amplitude ( RA ) - (M10-L5)/(M10+L5); (4) interdaily stability (IS): stability and (5) intradaily variability (IV), fragmentation of the rhythm. Cox proportional hazard models were constructed for time to (i) incident stroke (n=1,652); and (ii) post-stroke adverse outcomes (dementia, depression, disability, or death).

Results

Suppressed RA (lower M10 and higher L5) was associated with stroke risk after adjusting for demographics; the risk was highest in the lowest quartile [Q1] for RA (HR=1.62; 95% CI:1.36-1.93, p <0.001) compared to the top quartile [Q4]. Participants with later M10 midpoint timing (14:00-15:26, HR=1.26, CI:1.07-1.49, p =0.007) also had a higher risk for stroke than earlier (12:17-13:10) participants. A fragmented rhythm (IV) was also associated with a higher risk for stroke (Q4 vs. Q1; HR=1.27; CI:1.06-1.50, p =0.008), but differences in the stability of rhythms (IS) were not. Suppressed RA was associated with an increased risk of unfavorable post-stroke outcomes (Q1 vs. Q4; 1.78 [1.29-2.47]; p <0.001). All the associations were independent of age, sex, race, obesity, sleep disorders, cardiovascular diseases or risks, and other morbidity burdens.

Conclusion

Suppressed 24-h rest-activity rhythm may be a risk factor for stroke and an early indicator of major post-stroke adverse outcomes.

Work-Related Sleep Disorders: Causes and Impacts

Insufficient sleep syndrome, shift work disorder, and obstructive sleep apnea (OSA) not only significantly impact the health of affected individuals, but also pose a threat to public safety. This article describes the clinical manifestations and impact of these sleep disorders, particularly as they pertain to workers' health and those with safety-sensitive positions. Sleep deprivation, circadian rhythm disruptions, and excessive daytime sleepiness-hallmarks of insufficient sleep, shift work disorder, and OSA, respectively-all lead to a series of cognitive deficits and impaired concentration that affect workers in a wide variety of fields. We describe the health consequences of these disorders along with treatment strategies, with a focus on current regulatory standards and the under-recognition of OSA in commercial drivers. Given its large scale, there is a need for improved guidelines and regulations for the screening, diagnosis, treatment, and long-term follow-up of OSA in commercial motor vehicle drivers. Increased recognition of the ways in which these sleep disorders impact workers will pave the way for significant improvements in occupational health and safety.

Shiftwork sleep disorder and associated factors among nurses working at public hospitals in Harari Regional state and Dire Dawa Administration, Eastern Ethiopia: a cross-sectional study

BACKGROUND

Shiftwork sleep disorder is one of the most common health-related effects of Shiftwork, particularly among healthcare workers. It is a chronic condition that is directly related to a person's work schedule. In Ethiopia, although a mental health strategy is in place, little attention is given to studies that focus on shiftwork sleep disorders among nurses. This study aimed to determine the magnitude of shiftwork sleep disorder and associated factors among nurses working at public hospitals in Harari Regional State and the Dire Dawa Administration.

METHODS

Institutional based cross-sectional study was conducted from June 1-30, 2021 among 392 nurses selected by a simple random sampling technique. A structured interviewer-guided self-administered questionnaire was used for data collection. The International Classification of Sleep Disorders 3rd edition (ICSD-3), Bargen Insomnia Scale (BIS) and Epworth Sleepiness Scale were used to assess shift-work sleep disorder. The data were entered into EpiData and exported to SPSS for analysis. Bivariable logistic regression was used to see the association between the outcome and the explanatory variables. Bivariate and Multivariate analyses were performed, and AOR with 95% CI was used to measure the strength of the association. Those variables with a p-values of < 0.05 were considered as statistically significant.

RESULTS

In this study, the magnitude of shiftwork sleep disorder among nurses was 30.4% (95% CI: 25.4-34.5). Being female (AOR = 2.4, 95% CI: 1.3, 4.2), working an average number of nights > 11 per month in the last 12 months (AOR = 2.5, 95% CI: 1.3, 3.8), and khat use in the last 12 months (AOR = 4.9, 95% CI: 2.9, 8.7) were significantly associated with the shiftwork sleep disorder.

CONCLUSIONS

The study revealed that about one-third of the nurses had a shiftwork sleep disorder implying a high burden of the problem among nurses in the study setting, which endangers nurses, patients, and the healthcare system. Being female, working an average number of nights > 11 per month in the last 12 months, and khat use showed statistically significantly associated with the shiftwork sleep disorder. Early detection of shiftwork sleep disorder, having a policy on khat use and considering rest/recovery while scheduling work time should be addressed to prevent shiftwork sleep disorder.

Beyond sleep: A multidimensional model of chronotype

Chronotype can be defined as an expression or proxy for circadian rhythms of varied mechanisms, for example in body temperature, cortisol secretion, cognitive functions, eating and sleeping patterns. It is influenced by a range of internal (e.g., genetics) and external factors (e.g., light exposure), and has implications for health and well-being. Here, we present a critical review and synthesis of existing models of chronotype. Our observations reveal that most existing models and, as a consequence, associated measures of chronotype have focused solely or primarily on the sleep dimension, and typically have not incorporated social and environmental influences on chronotype. We propose a multidimensional model of chronotype, integrating individual (biological and psychological), environmental and social factors that appear to interact to determine an individual's true chronotype with potential feedback loops between these factors. This model could be beneficial not only from a basic science perspective but also in the context of understanding health and clinical implications of certain chronotypes as well as designing preventive and therapeutic approaches for related illnesses.

To what extent is circadian phase predictive of subjective jet lag in long-haul cabin crew pre- and post-trip?

Long-haul cabin crew regularly report misalignment between their circadian phase and the external world (i.e. jet lag). The extent to which changes in circadian phase relate to reported levels of jet lag remains unclear. The main aim of the present study was first to evaluate the relationship between objective (circadian phase) and subjective jet lag and second to explore the relative role of both subjective and objective psycho-behavioural factors in predicting the subjective experience of jet lag. Twenty-eight long-haul cabin crew completed questionnaires measuring diurnal preference, trip characteristics and subjective jet lag as a single and as a multidimensional measure. Sleep was monitored using actigraphy and urinary melatonin peak time was measured, at baseline (T1), e.g. before a long-haul trip and post-trip on the crew's first recovery day (T2). Subjective jet lag was also measured at both time points. At T1, later circadian phase related to increased unidimensional jet lag, however, a post-trip discrepancy was found between objective and subjective uni- and multidimensional jet lag measured at T2 and change from T1 to T2. After controlling for direction and size of circadian phase, increased uni- and multidimensional subjective jet lag was predicted by depressed mood states. The regression models including phase, diurnal preference, departure time on the outbound sector and arousal levels accounted for 28% of the variance in unidimensional jet lag and 53% of the variance in multidimensional jet lag. It was concluded that there is a discordance between objective and subjective jet lag post-trip. Further, subjective jet lag in long-haul cabin crew is better explained by mood impairment than circadian phase. The results are discussed with reference to the gap between subjective and objective jet lag and the role of psychology rather than just biology in the jet lag experience. The implications for improving health and safety in the workplace, through a better understanding of the role of human factors in the management of jet lag, are discussed.

TimeTeller for timing health: The potential of circadian medicine to improve performance, prevent disease and optimize treatment

Circadian medicine, the study of the effects of time on health and disease has seen an uprising in recent years as a means to enhance health and performance, and optimize treatment timing. Our endogenous time generating system -the circadian clock- regulates behavioural, physiological and cellular processes. Disruptions of the clock, via external factors like shift work or jet lag, or internal perturbations such as genetic alterations, are linked to an increased risk of various diseases like obesity, diabetes, cardiovascular diseases and cancer. By aligning an individual's circadian clock with optimal times for performing daily routines, physical and mental performance, and also the effectiveness of certain therapies can be improved. Despite the benefits of circadian medicine, the lack of non-invasive tools for characterizing the clock limits the potential of the field. TimeTeller is a non-invasive molecular/digital tool for the characterization of circadian rhythms and prediction of daily routines, including treatment timing, to unlock the potential of circadian medicine and implementing it in various settings. Given the multiple known and potentially yet unknown dependent health factors of individual circadian rhythms, the utility of this emerging biomarker is best exploited in data driven, personalized medicine use cases, using health information across lifestyle, care, and research settings.

Limits of entrainment of circadian neuronal networks

Circadian rhythmicity lies at the center of various important physiological and behavioral processes in mammals, such as sleep, metabolism, homeostasis, mood changes, and more. Misalignment of intrinsic neuronal oscillations with the external day-night cycle can disrupt such processes and lead to numerous disorders. In this work, we computationally determine the limits of circadian synchronization to external light signals of different frequency, duty cycle, and simulated amplitude. Instead of modeling circadian dynamics with generic oscillator models (e.g., Kuramoto-type), we use a detailed computational neuroscience model, which integrates biomolecular dynamics, neuronal electrophysiology, and network effects. This allows us to investigate the effect of small drug molecules, such as Longdaysin, and connect our results with experimental findings. To combat the high dimensionality of such a detailed model, we employ a matrix-free approach, while our entire algorithmic pipeline enables numerical continuation and construction of bifurcation diagrams using only direct simulation. We, thus, computationally explore the effect of heterogeneity in the circadian neuronal network, as well as the effect of the corrective therapeutic intervention of Longdaysin. Last, we employ unsupervised learning to construct a data-driven embedding space for representing neuronal heterogeneity.

Theoretical construct into blocks of actigraphic-derived sleep parameters

Actigraphic parameters can provide indication of people's sleep quality during their daily lives. However, there is a need for clear guidelines on the understanding of the different actigraphic parameters. The present study aims to propose a conceptual and theoretical framework for known actigraphic-derived parameters, which is able to describe the alternation between rest and wake phases during the nocturnal sleep, explaining their main characteristics and interrelations that can be replicated in future studies. Forty Sport Sciences students at the University of Milan (20 males; mean age ± SD, 22 ± 3 y) completed the validated Italian version of Morningness-Eveningness Questionnaire (MEQ) and wore an actigraph (Motion Watch 8®, Cambridge Neurotechnology, Cambridge, UK) for seven days. A framework was developed to depict the interactions between the actigraphic parameters and how they objectively describe sleep, according to which the parameters are organized into three different functional blocks related to different aspects of sleep. Correlations analyses were conducted to explore the relationships among the primary actigraphic parameters within and across the functional blocks. The proposed framework is a purely theoretical construct that provides a simple interpretation of known actigraphic parameters guiding researchers and practitioners in the use of these parameters either for research or clinical purposes.

The Molecular Relationship between Stress and Insomnia

The bi-directional relationship between sleep and stress has been actively researched as sleep disturbances and stress have become increasingly common in society. Interestingly, the brain and underlying neural circuits important for sleep regulation may respond uniquely to stress that leads to post-traumatic stress disorder (PTSD) and stress that does not. In stress that does not lead to PTSD, the hypothalamic-pituitary-adrenal axis (HPA) pathway is activated normally that results in sympathetic nervous system activation that allows the brain and body to return to baseline functioning. However, exposure to stress that leads to PTSD, causes enhanced negative feedback of this same pathway and results in long-term physiological and psychological changes. In this review, how stress regulates glucocorticoid signaling pathways in brain glial cells called astrocytes, and then mediates stress-induced insomnia are examined. Astrocytes are critical sleep regulatory cells and their connections to sleep and stress due to disturbed glucocorticoid signaling provide a novel mechanism to explain how stress leads to insomnia. This review will examine the interactions of stress neurobiology, astrocytes, sleep, and glucocorticoid signaling pathways and will examine the how stress that leads to PTSD and stress that does not impacts sleep-regulatory processes.

Shift Work Disorder Index: initial validation and psychosocial associations in a sample of nurses

STUDY OBJECTIVES

Shift work is common yet does not always result in Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5)-defined shift work sleep disorder (SWD). This study reports on the reliability and validity of the DSM-5 informed Shift Work Disorder Index (SWDI), the presence of probable SWD in nurses, and demographic, sleep, and psychosocial correlates.

METHODS

Nurses (n = 454) completed the SWDI, psychosocial, and demographic questionnaires. Of the sample, n = 400 completed 14 days of sleep diaries, actigraphy, and additional questionnaires.

RESULTS

The global SWDI demonstrated excellent internal consistency (α = .94), as well as good convergent and divergent validity in the nurse sample. Thirty-one percent of nurses were past-month shift workers, with 14% (ie, 44% of shift workers) having probable SWD based on SWDI. Nurses who worked shift work and/or met SWD criteria were more likely to be younger and unmarried and less likely to have children than day workers and reported greater evening chronotype, insomnia, nightmares, and sleep-related impairment, greater depression, anxiety, posttraumatic stress, and perceived stress symptoms, as well as later and more variable sleep midpoint (actigraphy), shorter sleep duration (actigraphy, diaries), and lower sleep efficiency (diaries).

CONCLUSIONS

The SWDI is an efficient and valid self-report assessment of DSM-5-defined SWD. Shift work and/or SWD were prevalent and associated with worse sleep and psychosocial health, particularly among nurses with probable SWD.

CITATION

Taylor DJ, Dietch JR, Wardle-Pinkston S, et al. Shift Work Disorder Index: initial validation and psychosocial associations in a sample of nurses. J Clin Sleep Med. 2022;18(10):2339-2351.

Homeostatic response to sleep deprivation and circadian rhythmicity are intact in older adults with insomnia

STUDY OBJECTIVES

We examined whether homeostatic sleep drive and circadian rhythmicity differ in older adults with insomnia (OAI) compared to older good sleepers (GS).

METHODS

OAI (n = 37) and GS (n = 30) participated in a 60-h in-lab study with sleep deprivation and constant routine paradigms. Homeostatic sleep drive was assessed by examining the effect of sleep deprivation on delta EEG power and theta EEG power, and repeated sleep latency tests. Circadian rhythm was assessed with salivary melatonin (phase and amplitude), core body temperature (phase, amplitude, and mesor), and sleep latency during a constant routine paradigm. Mixed models were used to assess interactions of group (OAS vs GS) with homeostatic sleep and circadian effects.

RESULTS

Compared to GS, OAI showed a greater linear increase in waking theta power during sleep deprivation, but the two groups did not show differential responses to sleep deprivation in delta EEG, or in repeated sleep latency tests. The two groups did not differ in circadian phase or amplitude of melatonin or core body temperature rhythms. OAI had a significantly elevated core body temperature mesor compared to GS.

CONCLUSIONS

Homeostatic response to sleep deprivation was intact in OAI compared to GS; theta EEG power suggested a greater homeostatic response in OAI. Circadian rhythm amplitude and phase were similar in OAI compared to GS. Elevated body temperature mesor in OAI may indicate elevated physiological arousal. These findings suggest that effective treatments for insomnia in older adults may leverage intact sleep and circadian regulatory mechanisms, rather than repair defective sleep and circadian regulation.

Sleep disruption induces activation of inflammation and heightens risk for infectious disease: Role of impairments in thermoregulation and elevated ambient temperature

Thermoregulation and sleep are tightly coordinated, with evidence that impairments in thermoregulation as well as increases in ambient temperature increase the risk of sleep disturbance. As a period of rest and low demand for metabolic resources, sleep functions to support host responses to prior immunological challenges. In addition by priming the innate immune response, sleep prepares the body for injury or infection which might occur the following day. However when sleep is disrupted, this phasic organization between nocturnal sleep and the immune system becomes misaligned, cellular and genomic markers of inflammation are activated, and increases of proinflammatory cytokines shift from the nighttime to the day. Moreover, when sleep disturbance is perpetuated due to thermal factors such as elevated ambient temperature, the beneficial crosstalk between sleep and immune system becomes further imbalanced. Elevations in proinflammatory cytokines have reciprocal effects and induce sleep fragmentation with decreases in sleep efficiency, decreases in deep sleep, and increases in rapid eye movement sleep, further fomenting inflammation and inflammatory disease risk. Under these conditions, sleep disturbance has additional potent effects to decrease adaptive immune response, impair vaccine responses, and increase vulnerability to infectious disease. Behavioral interventions effectively treat insomnia and reverse systemic and cellular inflammation. Further, insomnia treatment redirects the misaligned inflammatory- and adaptive immune transcriptional profiles with the potential to mitigate risk of inflammation-related cardiovascular, neurodegenerative, and mental health diseases, as well as susceptibility to infectious disease.

Methodologies and Wearable Devices to Monitor Biophysical Parameters Related to Sleep Dysfunctions: An Overview

Sleep is crucial for human health from metabolic, mental, emotional, and social points of view; obtaining good sleep in terms of quality and duration is fundamental for maintaining a good life quality. Over the years, several systems have been proposed in the scientific literature and on the market to derive metrics used to quantify sleep quality as well as detect sleep disturbances and disorders. In this field, wearable systems have an important role in the discreet, accurate, and long-term detection of biophysical markers useful to determine sleep quality. This paper presents the current state-of-the-art wearable systems and software tools for sleep staging and detecting sleep disorders and dysfunctions. At first, the paper discusses sleep's functions and the importance of monitoring sleep to detect eventual sleep disturbance and disorders. Afterward, an overview of prototype and commercial headband-like wearable devices to monitor sleep is presented, both reported in the scientific literature and on the market, allowing unobtrusive and accurate detection of sleep quality markers. Furthermore, a survey of scientific works related the effect of the COVID-19 pandemic on sleep functions, attributable to both infection and lifestyle changes. In addition, a survey of algorithms for sleep staging and detecting sleep disorders is introduced based on an analysis of single or multiple biosignals (EEG-electroencephalography, ECG-electrocardiography, EMG-electromyography, EOG-electrooculography, etc.). Lastly, comparative analyses and insights are provided to determine the future trends related to sleep monitoring systems.

Sleep and spa therapies: What is the role of balneotherapy associated with exercise? A systematic review

Balneotherapy and exercise are potential factors influencing sleep through several physiological pathways and relaxing effects. This review aims to assess whether balneotherapy can improve sleep quality in concomitance or not with exercise. The research was conducted on Medline, Scopus, PubMed, Web of Science, and Cochrane Library databases. The current review followed PRISMA reporting guidelines and involves twenty-one articles grouped into four sections based on the characteristics of the balneotherapy protocol: 1.a Balneotherapy-thermal water immersion alone (five studies); 1.b Balneotherapy-thermal water immersion with other spa treatments (six studies); 2.a Balneotherapy and physical exercise-balneotherapy and out-of-the-pool physical exercise (eight studies); 2.b Balneotherapy and physical exercise-balneotherapy and in-pool physical exercise (three studies). Apart from healthy or sub-healthy subjects, patients recruited in the studies were affected by fibromyalgia, ankylosing spondylitis, osteoarthritis, musculoskeletal pain, subacute supraspinatus tendinopathy, and mental disorders. Duration, number of sessions, and study protocols are very different from each other. Only one study objectively evaluated sleep, whereas the others used subjective sleep assessment methods. Eight studies considered sleep as a primary outcome and ten as secondary. Sixteen out of twenty-one studies described improvements in self-perceived sleep quality. Thus, balneotherapy associated with other spa treatments and physical exercise seems to be effective in improving self-perceived sleep quality. However, the miscellany of treatments makes it difficult to discern the isolated effects of balneotherapy and physical exercise. Future studies should consider using an objective sleep assessment method and describing the pathways and physiological mechanisms that could provoke sleep changes during balneotherapy treatments.

Cerebellar Microstructural Abnormalities in Parkinson's Disease: a Systematic Review of Diffusion Tensor Imaging Studies

Diffusion tensor imaging (DTI) is now having a strong momentum in research to evaluate the neural fibers of the CNS. This technique can study white matter (WM) microstructure in neurodegenerative disorders, including Parkinson's disease (PD). Previous neuroimaging studies have suggested cerebellar involvement in the pathogenesis of PD, and these cerebellum alterations can correlate with PD symptoms and stages. Using the PRISMA 2020 framework, PubMed and EMBASE were searched to retrieve relevant articles. Our search revealed 472 articles. After screening titles and abstracts, and full-text review, and implementing the inclusion criteria, 68 papers were selected for synthesis. Reviewing the selected studies revealed that the patterns of reduction in cerebellum WM integrity, assessed by fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity measures can differ symptoms and stages of PD. Cerebellar diffusion tensor imaging (DTI) changes in PD patients with "postural instability and gait difficulty" are significantly different from "tremor dominant" PD patients. Freezing of the gate is strongly related to cerebellar involvement depicted by DTI. The "reduced cognition," "visual disturbances," "sleep disorders," "depression," and "olfactory dysfunction" are not related to cerebellum microstructural changes on DTI, while "impulsive-compulsive behavior" can be linked to cerebellar WM alteration. Finally, higher PD stages and longer disease duration are associated with cerebellum white matter alteration depicted by DTI. Depiction of cerebellar white matter involvement in PD is feasible by DTI. There is an association with disease duration and severity and several clinical presentations with DTI findings. This clinical-imaging association may eventually improve disease management.

Circadian Rhythm Sleep-Wake Disorders in Older Adults

The timing, duration, and consolidation of sleep result from the interaction of the circadian timing system with a sleep-wake homeostatic process. When aligned and functioning optimally, this allows for wakefulness throughout the day and a long consolidated sleep episode at night. Changes to either the sleep regulatory process or how they interact can result in an inability to fall asleep at the desired time, difficulty remaining asleep, waking too early, and/or difficulty remaining awake throughout the day. This mismatch between the desired timing of sleep and the ability to fall asleep and remain asleep is a hallmark of a class of sleep disorders called the circadian rhythm sleep-wake disorders. In this updated article, we discuss typical changes in the circadian regulation of sleep with aging; how age influences the prevalence, diagnosis, and treatment of circadian rhythm sleep disorders; and how neurologic diseases in older patient impact circadian rhythms and sleep.

Travelers' perceptions of jetlag and travel fatigue: A scoping review

Effective management strategies for jetlag have largely been studied and evaluated through the lens of circadian science and biological rhythms. Jetlag is mostly self-managed by the individual. The most effective strategies require individuals to make behavioral changes to carefully alter sleep-wake schedules and time light exposure. However, travelers' perceptions, including their experiences, beliefs about jetlag/travel fatigue, and management expectations remain unclear. Therefore, the aim of this scoping review was to systematically synthesize the literature to understand what is currently known about travelers' perceptions of jetlag and travel fatigue. A literature search was conducted through EMBASE, PsycINFO, PubMed and Scopus generating 1164 results (2 articles known to authors), which were screened against our inclusion criteria. Twenty-two studies including data from 3952 participants were evaluated for its study design and traveler-centered outcome measures across the domains of: 1) Traveler Health Beliefs and Knowledge about Jetlag and Travel Fatigue; 2) Experience of Jetlag and Travel Fatigue 3) Traveler Priorities; 4) Self-reported Management Strategies for Jetlag and Travel Fatigue; and 5) User Experiences of Management Strategies. Synthesis of results suggests a potential mismatch between researchers' focus on circadian misalignment and travelers' focus on air travel comfort. A better understanding of the beliefs, attitudes, knowledge, satisfaction, experiences, and expectations about jetlag and travel fatigue will better enable the development of interventions that align with traveler priorities.

Daily rhythms in right-sided and left-sided temporal lobe epilepsy

Introduction

Epilepsy is closely related to daily rhythms, such as the sleep-wake cycle. The objective of this study was to evaluate the relationship between drug-resistant temporal lobe epilepsy (TLE) and the parameters related to the sleep-wake cycle, seizure time and epilepsy laterality.

Methods

Consecutive patients admitted to the video electroencephalogram unit with a diagnosis of TLE were enrolled. Patients were divided into two groups: those with left TLE (LTLE) and those with right TLE (RTLE). They then remained in the conditions of 12-hour light, 12-hour darkness. Demographic data, treatment, number and time of seizure occurrence, sleep diary, morningness-eveningness questionnaire, Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale were recorded.

Results

In total, 74 patients with TLE, 43 with LTLE and 31 with RTLE, were studied. RTLE patients showed a significant preference for morningness. Patients treated with benzodiazepines showed worse sleep quality and greater daytime sleepiness. Patients who did not report any clear predominance and patients who reported seizures during wakefulness had significantly more seizures during wakefulness and patients who reported sleep predominance had more seizures during sleep (p>0.001). The LTLE group had a greater number of seizures from 8 to 16 hours, unlike the RTLE group, which had a uniform distribution (p=0.008).

Conclusions

This was a prospective study of patients with drug-resistant TLE performed in a controlled environment to study the impact of daily rhythms, seizure frequency and seizure distribution. Laterality seems to be a key factor in seizure distribution.

Study protocol for the Shifting Weight using Intermittent Fasting in night shift workers (SWIFt) study: a three-arm randomised controlled trial comparing three weight loss strategies in night shift workers with obesity

INTRODUCTION

Shift workers are at an increased risk of developing obesity and type 2 diabetes. Eating and sleeping out of synchronisation with endogenous circadian rhythms causes weight gain, hyperglycaemia and insulin resistance. Interventions that promote weight loss and reduce the metabolic consequences of eating at night are needed for night shift workers. The aim of this study is to examine the effects of three weight loss strategies on weight loss and insulin resistance (HOMA-IR) in night shift workers.

METHODS AND ANALYSIS

A multisite 18-month, three-arm randomised controlled trial comparing three weight loss strategies; continuous energy restriction; and two intermittent fasting strategies whereby participants will fast for 2 days per week (5:2); either during the day (5:2D) or during the night shift (5:2N). Participants will be randomised to a weight loss strategy for 24 weeks (weight loss phase) and followed up 12 months later (maintenance phase). The primary outcomes are weight loss and a change in HOMA-IR. Secondary outcomes include changes in glucose, insulin, blood lipids, body composition, waist circumference, physical activity and quality of life. Assessments will be conducted at baseline, 24 weeks (primary endpoint) and 18 months (12-month follow-up). The intervention will be delivered by research dietitians via a combination of face-to-face and telehealth consultations. Mixed-effect models will be used to identify changes in dependent outcomes (weight and HOMA-IR) with predictor variables of outcomes of group, time and group-time interaction, following an intention-to-treat approach.

ETHICS AND DISSEMINATION

The study protocol was approved by Monash Health Human Research Ethics Committee (RES 19-0000-462A) and registered with Monash University Human Research Ethics Committee. Ethical approval has also been obtained from the University of South Australia (HREC ID: 202379) and Ambulance Victoria Research Committee (R19-037). Results from this trial will be disseminated via conference presentations, peer-reviewed journals and student theses.

TRIAL REGISTRATION NUMBER

Australian New Zealand Clinical Trials Registry (ACTRN-12619001035112).

Air travellers' experiences and understanding of jetlag and perceptions of management strategies: a qualitative study

Jetlag is largely self-managed by the individual traveller. This paper explores the lived experiences of air travellers, their understanding of jetlag, and their perceptions of management strategies. 32 international travellers (mean age = 31, SD: 15 years; 47% female, mean flight duration = 16, SD: 6 hours) were interviewed. Interviews were recorded, transcribed verbatim and analysed using the Framework Approach. Analysis of the qualitative data revealed three emergent themes: Travel beliefs and experiences, Impact of jetlag, and Approaches to jetlag management. Participants' experience of jetlag was described in terms of the entire journey with no distinction made between circadian disruption and travel fatigue. Management strategies revolved around needs for comfort and avoiding fatigue, and were mostly guided by somatic symptom cues, prior travel experiences, or the experiential advice from others. Our findings highlight the need for traveller involvement in co-designing evidence-based interventions for jetlag to enhance their transferability into the real world. Practitioner summaryQualitative findings highlighted jetlag as encapsulating the entire journey, and not limited to post-flight circadian disruptions during international travel. Jetlag management interventions need to address issues of circadian misalignment together with travel fatigue and in-flight discomfort through behavioural and nutritional strategies. Travel context and environmental factors such as airport facilities also influenced perceived jetlag severity.

The Effect of Change of Working Schedule on Health Behaviors: Evidence from the Korea Labor and Income Panel Study (2005–2019)

This study investigated whether changes in work schedule are associated with health behavior changes. We used data from the Korea Labor and Income Panel Survey from 2005 to 2019. A generalized estimating equation model was used to assess the association between changes of work schedules (day–day, day–shift, shift–day, and shift–shift) and health behaviors. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated after adjusting for general and socioeconomic characteristics. Fixed daytime work was observed for 25,716 person-years, and fixed shift work was observed for 2370 person-years out of the total 4046 participants during a 14 year period. Workers who changed their work schedule from fixed daytime to shift work and from shift to fixed daytime work contributed to 670 and 739 person-years, respectively. Considering continuous fixed daytime workers as a reference group, continuous exposure to shift work (aOR 1.11, CI 1.01–1.26) and changes from fixed daytime to shift work (aOR 1.18, CI 1.05–1.44) were significantly associated with an increased risk of changing either smoking or drinking behavior to unhealthy patterns. The results of our study suggest that workers who work irregular shift times, in contrast to those with more standard, regular work schedules, are at a higher risk of changing smoking and/or drinking behavior to unhealthy patterns.

The Development, Implementation, and Feasibility of a Circadian, Light, and Sleep Skills Program for Shipboard Military Personnel (CLASS-SM)

Service members face unique barriers to sufficient and high quality sleep. In the present study, a circadian, light, and sleep skills program for shipboard military personnel (CLASS-SM) was designed to encourage and inform strategies that support optimal sleep and circadian health in the context of those barriers. Phase 1 included program development and refinement via an iterative formative evaluation, including structured interviews with service members and feedback from veterans and experts, resulting in further tailoring to the population. In Phase 2, the highly tailored program was administered to shipboard personnel (n = 55), and acceptability indicators were measured. Sleep- and circadian-related knowledge (pre- and post-program) and the perceived relevance of, and satisfaction with, program content (post-program) were assessed. Before the intervention, most individuals were unaware that 7−9 h of sleep is recommended (72%) and had little understanding of the physiological effects of light; however, knowledge scores increased significantly post-program, from 51% to 88% correct (p < 0.0001). Reception was positive, with high reported satisfaction and relevance. Most individuals reported that they learned something new (89%), planned to use one or more learned strategies (100%), and intended to share learned information with others (85%); the physiological effects of light and circadian rhythms were the content areas most frequently reported as new and useful. The results demonstrate the need for, and feasibility of, the delivery of this program in operational environments.

Time-of-day effect on motor coordination in youth

The evaluation of motor coordination is important for diagnosing children and adolescents with motor impairments. However, motor coordination may be affected by time-of-day effects, and thus, the intra-day variation could subsequently influence the assessment accuracy of the standardized test used in the diagnostic process. To the best of our knowledge, no study has been conducted to examine this possibility. Therefore, the purpose of this study was to investigate the time-of-day effect on motor coordination. A convenience sample of 25 youth (17-21 years) were recruited from local high schools and a local university. The Bruininks-Oseretsky Test of Motor Proficiency - Second Edition (Short Form) was administered at three different times (morning, noon, and afternoon) over three days to explore the potential time-of-day effect on motor coordination. The starting time of the test on the first day was counterbalanced. Other factors that could potentially impact motor performance were also measured, including physical activity, chronotype, and time-since-awakening. A statistically significant main effect of time-of-day was found on overall motor coordination (p< .01) and the domain of Manual Coordination (p< .01). The time-of-day effect on the domain of Strength & Agility (p = .055) was just above the threshold of statistical significance. Further analysis showed that overall motor coordination was better at noon (p< .01) and in the afternoon (p= .052) than in the morning, whereas manual coordination was the worst in the morning (p's < .01). Strength and agility were also significantly better at noon than in the morning (p< .01). In addition, poor motor coordination in the morning was also related to longer time-since-awakening. Overall, this study identifies the time-of-day effect on motor coordination that could lead to the inconsistent classification of motor performance. Therefore, in order to avoid the potential misclassification of motor coordination, health professionals should take into account the time-of-day effect on motor coordination and the possible impact of time-since-awakening while administering the assessment in the morning.

Assessment of dim light melatonin onset based on plasma and saliva samples

Melatonin (MELA) is a nocturnal hormone involved in the regulation of the circadian rhythm. MELA can be detected in plasma and saliva, and its salivary concentration strongly correlates with its plasma concentration. Dim light melatonin onset (DLMO) is considered to be the most accurate objective marker for assessing the circadian phase. The purpose of the study was to establish a method for the determination of MELA in plasma and saliva based on the liquid chromatography with tandem mass spectrometry (LC-MS/MS) and compare DLMO using both plasma and saliva matrices. The validation of the LC-MS/MS methods was performed in accordance with the European Medicines Agency (EMA) guideline. The study was conducted on a group of 21 volunteers, male and females, aged 26-54 years. Plasma and saliva were collected at five time points: between 20:00 and 00:00 hours. The MELA concentration was determined by the LC-MS/MS. The DLMO was considered as the point in time when MELA concentration exceeds 20 pg/mL in plasma and 7 pg/mL in saliva. The correlation coefficient between the plasma and salivary MELA concentration was r = 0.764 (p < .001). The ratio of the plasma/saliva MELA concentrations was 2.87. The mean time of the DLMO in the plasma was 21:30 ± 0:45 hours, and in the saliva was as follows: 21:34 ± 1:00 hours. The correlation between the DLMO, calculated based on the plasma and saliva MELA profiles, was r = 0.679 (p < .05). The determination of salivary MELA concentration using LC-MS/MS allows for the determination of the DLMO. Our method may be applied in clinical practice for the diagnosis and monitoring of circadian rhythm disorders.Abbreviations: CE: Collision Energy; CID: Collision-Induced Dissociation; DL: Desolvation Module; DLMO: Dim Light Melatonin Onset; EFSA: European Food Safety Authority; EMA: European Medicines Agency; ESI: electrospray ionization; HB: heat block; HPLC: high performance liquid chromatography; IS: internal standard; K₃EDTA: ethylenediaminetetraacetic acid tripotassium salt; LC-MS/MS: liquid chromatography with tandem mass spectrometry; LLE: liquid-liquid extraction; LLOQ: lower limit of quantification; MELA: melatonin; MELA-D₄: melatonin-d₄; MRM: multiple reaction monitoring; Q1: quadrupole 1; Q3: quadrupole 3; RE: relative error; RIA: radioimmunoassay; RSD: relative standard deviation; SD: standard deviation; ULOQ: upper limit of quantification.

Self-reported sleep duration and timing: A methodological review of event definitions, context, and timeframe of related questions

Study Objectives

Clinical and population health recommendations are derived from studies that include self-report. Differences in question wording and response scales may significantly affect responses. We conducted a methodological review assessing variation in event definition(s), context (i.e., work- versus free-day), and timeframe (e.g., "in the past 4 weeks") of sleep timing/duration questions.

Methods

We queried databases of sleep, medicine, epidemiology, and psychology for survey-based studies and/or publications with sleep duration/timing questions. The text of these questions was thematically analyzed.

Results

We identified 53 surveys with sample sizes ranging from 93 to 1,185,106. For sleep duration, participants reported nocturnal sleep (24/44), sleep in the past 24-hours (14/44), their major sleep episode (3/44), or answered unaided (3/44). For bedtime, participants reported time into bed (19/47), first attempt to sleep (16/40), or fall-asleep time (12/47). For wake-time, participants reported wake-up time (30/43), the time they "get up" (7/43), or their out-of-bed time (6/43). Context guidance appeared in 18/44 major sleep duration, 35/47 bedtime, and 34/43 wake-time questions. Timeframe was provided in 8/44 major sleep episode duration, 16/47 bedtime, and 10/43 wake-time questions. One question queried the method of awakening (e.g., by alarm clock), 18 questions assessed sleep latency, and 12 measured napping.

Conclusion

There is variability in the event definition(s), context, and timeframe of questions relating to sleep. This work informs efforts at data harmonization for meta-analyses, provides options for question wording, and identifies questions for future surveys.

Impacts of travel distance and travel direction on back-to-back games in the National Basketball Association

STUDY OBJECTIVES

Travel fatigue and circadian disruptions are known factors that can hinder performance in professional athletes. The present study focused on travel distance and direction on back-to-back games over the 2013-2020 seasons in the National Basketball Association (NBA).

METHODS

The outcomes were based on winning percentage with additional covariates including the direction of travel (eastward or westward), the distance traveled (0-500 km; 501-1,000 km; 1,001-1,500 km; 1,501 km and more), team quality, and season. If a team played both games of a back-to-back sequence on the road, they were considered Away-Away; if a team played the first game of a back-to-back sequence at home they were considered Home-Away; if a team played the first game of a back-to-back sequence on the road they were considered Away-Home.

RESULTS

The sequence Away-Home significantly increases the likelihood of winning compared with the Away-Away and Home-Away sequences: 54.4% (95% confidence interval [CI], 54.4%-54.5%), 39.2% (95% CI, 37.2%-41.2%), and 36.8% (95% CI, 36.7%-36.8%), respectively. When teams travel back home, every additional 500 km reduces the likelihood of winning by approximately 4% (P = .038). Finally, after withdrawing the Away-Home sequence, traveling eastward significantly increases the chance of winning (P = .024) compared with westward travel but has no significant impact on the probability of winning compared with neutral time zone travel (P = .091).

CONCLUSIONS

The accumulation of travel fatigue and the chronic circadian desynchronization that occurs over the NBA season can acutely disturb sleep and recovery. It appears that tailored sleep and recovery strategies need to be dynamically developed throughout the season to overcome the different challenges of the NBA schedule.

CITATION

Charest J, Samuels CH, Bastien CH, Lawson D, Grandner MA. Impacts of travel distance and travel direction on back-to-back games in the National Basketball Association. J Clin Sleep Med. 2021;17(11):2269-2274.

The endogenous circadian system worsens asthma at night independent of sleep and other daily behavioral or environmental cycles

Asthma often worsens at night. To determine if the endogenous circadian system contributes to the nocturnal worsening of asthma, independent of sleep and other behavioral and environmental day/night cycles, we studied patients with asthma (without steroid use) over 3 wk in an ambulatory setting (with combined circadian, environmental, and behavioral effects) and across the circadian cycle in two complementary laboratory protocols performed in dim light, which separated circadian from environmental and behavioral effects: 1) a 38-h "constant routine," with continuous wakefulness, constant posture, 2-hourly isocaloric snacks, and 2) a 196-h "forced desynchrony" incorporating seven identical recurring 28-h sleep/wake cycles with all behaviors evenly scheduled across the circadian cycle. Indices of pulmonary function varied across the day in the ambulatory setting, and both laboratory protocols revealed significant circadian rhythms, with lowest function during the biological night, around 4:00 AM, uncovering a nocturnal exacerbation of asthma usually unnoticed or hidden by the presence of sleep. We also discovered a circadian rhythm in symptom-based rescue bronchodilator use (β2-adrenergic agonist inhaler) whereby inhaler use was four times more likely during the circadian night than day. There were additive influences on asthma from the circadian system plus sleep and other behavioral or environmental effects. Individuals with the lowest average pulmonary function tended to have the largest daily circadian variations and the largest behavioral cycle effects on asthma. When sleep was modeled to occur at night, the summed circadian, behavioral/environmental cycle effects almost perfectly matched the ambulatory data. Thus, the circadian system contributes to the common nocturnal worsening of asthma, implying that internal biological time should be considered for optimal therapy.

Effects of Shift Work in a Sample of Italian Nurses: Analysis of Rest-Activity Circadian Rhythm

Shift work can lead to circadian desynchronization due to temporary misalignment between working hours and physiological and behavioral functioning, resulting in compromised health, insomnia, worsening of sleep quality, reduced ability to work during waking hours, and increased cardiovascular risk. We evaluated the effects of shift work on the rest-activity circadian rhythm (RAR) and health status of Italian orthopaedic nurses. The study population was 59 nurses: 44 worked the night shift and 15 worked the day shift. All carried out continuous 5-day actigraphic monitoring to assess RAR, including both the working and the rest period. The rhythmometric analysis showed that, during the working period, the night shift nurses had a significantly lower amplitude than the day shift nurses (p < 0.001), and the acrophase was significantly different between the two groups (p < 0.01). When we stratified the two groups by median body mass index (<25 kg/m² normal weight and ≥25 kg/m² overweight), during the working period, we noted a significantly lower amplitude for both the normal weight and the overweight nurses who worked the night shift (p < 0.01 and p < 0.001, normal weight and overweight respectively). The current findings suggest the need for further study of the relationship between activity levels and shift work.

Morningness-eveningness assessment from mobile phone communication analysis

Human behaviour follows a 24-h rhythm and is known to be governed by the individual chronotypes. Due to the widespread use of technology in our daily lives, it is possible to record the activities of individuals through their different digital traces. In the present study we utilise a large mobile phone communication dataset containing time stamps of calls and text messages to study the circadian rhythms of anonymous users in a European country. After removing the effect of the synchronization of East-West sun progression with the calling activity, we used two closely related approaches to heuristically compute the chronotypes of the individuals in the dataset, to identify them as morning persons or “larks” and evening persons or “owls”. Using the computed chronotypes we showed how the chronotype is largely dependent on age with younger cohorts being more likely to be owls than older cohorts. Moreover, our analysis showed how on average females have distinctly different chronotypes from males. Younger females are more larkish than males while older females are more owlish. Finally, we also studied the period of low calling activity for each of the users which is considered as a marker of their sleep period during the night. We found that while “extreme larks” tend to sleep more than “extreme owls” on the weekends, we do not observe much variation between them on weekdays. In addition, we have observed that women tend to sleep even less than males on weekdays while there is not much difference between them on the weekends.

Network pharmacology-based and molecular docking prediction of the active ingredients and mechanism of ZaoRenDiHuang capsules for application in insomnia treatment

BACKGROUND

The ZaoRenDiHuang (ZRDH) capsule is widely used in clinical practice and has significant therapeutic effects on insomnia. However, its active ingredients and mechanisms of action for insomnia remain unknown. In this study, network pharmacology was employed to elucidate the potential anti-insomnia mechanisms of ZRDH.

METHODS

The potential active ingredients of ZRDH were obtained from the Traditional Chinese Medicine Systems Pharmacology Database. Possible targets were predicted using SwissTargetPrediction tools. The insomnia-related targets were identified using the therapeutic target database, Drugbank database, Online Mendelian Inheritance in Man database, and gene-disease associations database. A compound-target-disease network was constructed using Cytoscape for visualization. Additionally, the protein functional annotation and identification of signaling pathways of potential targets were performed using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses using the Metascape platform.

RESULTS

In this study, 61 anti-insomnia components and 65 anti-insomnia targets of ZRDH were filtered through database mining. The drug-disease network was constructed with five key components. Sixty-five key targets were identified using topological analysis. Docking studies indicated that bioactive compounds could stably bind to the pockets of target proteins. Through data mining and network analysis, the GO terms and KEGG annotation suggested that the neuroactive ligand-receptor interaction, serotonergic synapse CAMP signaling, HIF-1a signaling, and toll-like receptor signaling pathways play vital roles against insomnia.

CONCLUSION

The potential mechanisms of ZRDH treatment for insomnia involve multiple components, targets, and pathways. These findings provide a reference for further investigations into the mechanisms underlying ZRDH treatment of insomnia.

Concordance of Chronotype Categorisations Based on Dim Light Melatonin Onset, the Morningness-Eveningness Questionnaire, and the Munich Chronotype Questionnaire

Chronotype reflects circadian timing and can be determined from biological markers (e.g., dim light melatonin onset; DLMO), or questionnaires (e.g., Morningness-Eveningness Questionnaire; MEQ, or Munich Chronotype Questionnaire; MCTQ). The study’s aim was to quantify concordance between chronotype categorisations based on these measures. A total of 72 (36f) young, healthy adults completed the MEQ and MCTQ and provided saliva samples hourly in dim light during the evening in a laboratory. The corrected midpoint of sleep on free days (MSF_sc) was derived from MCTQ, and tertile splits were used to define early, intermediate and late DLMO-CT, MEQ-CT and MSF_sc-CT chronotype categories. DLMO correlated with MEQ score (r = −0.25, p = 0.035) and MSF_sc (r = 0.32, p = 0.015). For early, intermediate and late DLMO-CT categories, mean(SD) DLMO were 20:25(0:46), 21:33(0:10) and 23:03(0:53). For early, intermediate and late MEQ-CT categories, mean(SD) MEQ scores were 60.5(5.3), 51.4(2.9) and 40.8 (5.0). For early, intermediate and late MSF_sc-CT categories, mean(SD) MSF_sc were 03:23(0:34), 04:37(0:12) and 05:55(0:48). Low concordance of categorisations between DLMO-CT and MEQ-CT (37%), and between DLMO-CT and MSF_sc-CT (37%), suggests chronotype categorisations depend on the measure used. To enable valid comparisons with previous results and reduce the likelihood of misleading conclusions, researchers should select measures and statistical techniques appropriate to the construct of interest and research question.

Setting Objective Clinical Assessment Tools for Circadian Rhythm Sleep-Wake Disorders - A Community-Based Cross-Sectional Epidemiological Study

INTRODUCTION

Circadian rhythm sleep-wake disorder (CRSWD) is an often-misdiagnosed group of sleep disturbances with limited data concerning diagnostic and therapeutic algorithms in the general population. Therefore, reported prevalence varies in the literature due to different case definitions, methodological, and environmental factors.

OBJECTIVES

The purpose of our cross-sectional study was to estimate the prevalence of CRSWD in the general population of Cyprus and to suggest clinical parameters for the assessment of atypical sleep schedules. The estimation was carried out by introducing normal preset sleep time limits, according to the imposed local environment and by administering well-established questionnaires for symptoms and consequence dysfunction, as objective evaluation tools.

METHODS

In a nationwide epidemiological survey, 4118 Cypriot adult participants, selected and stratified to represent the general population, were interviewed on sleep habits and complaints by computer-assisted telephone interviewing (CATI). In the second stage, 250 adults were randomly selected from the initial representative sample, for a CRSWD assessment. According to the proposed diagnostic criteria, patients were interviewed about sleepiness and/or insomnia, and daytime dysfunction (fatigue, anxiety, and depression). They were also assessed by a weekly sleep diary for sleep schedules. Finally, all participants underwent a Type III Sleep Study, to rule out obstructive sleep apnea.

RESULTS

From 195 enrolled participants (response rate 78%), 25 individuals (12.8%) met the criteria for CRSWD. The two most prevalent disorders were delayed sleep-wake phase disorder (DSWPD) (10pts, 5.1%) and shift work sleep disorder (SWD) (13, 6.7%). Less prevalent disorders included irregular sleep-wake rhythm disorder (ISWRD) (1, 0.5%) and advanced sleep-wake phase disorder (ASWPD) (1, 0.5%).

CONCLUSIONS

According to our data, CRSWDs are common in the general population of Cyprus, especially DSWPD and SWD. Affected individuals usually suffer from sleep deprivation and complain about insomnia, sleepiness and depression.

Circadian characteristics of the rest-activity rhythm, executive function, and glucose fluctuations in young adults with type 1 diabetes

Circadian alignment is an important element in individual health, and one behavioral marker, rest-activity rhythm, could influence self-management in young adults with type 1 diabetes (T1D). Little is known about the rest-activity rhythms, executive function, and glycemia among young adults with type 1 diabetes (T1D). The purpose of this study was to evaluate parametric and nonparametric circadian characteristics of the rest-activity rhythm and the associations between these variables, sleep-wake behavior, executive function, and glycemia among young adults with T1D. Young adults with T1D, recruited from diabetes clinics, wore wrist actigraphs and a continuous glucose monitor (CGM) concurrently for 6-14 days. Participants completed a 3-minute Trail Making Test on paper and electronic questionnaires - 8-item PROMIS v1.0 Emotional Distress Scale, 17-item Diabetes Distress Scale, including twice-daily Pittsburgh sleep diaries. Cosinor and nonparametric analyses were used to compute the rest-activity rhythm parameters, and linear regression modeling procedures were performed to determine the associations among the study variables. The sample included 46 young adults (mean age 22.3 ± 3.2; 32.6% male; 84.8% non-Hispanic White, HbA1c mean 7.2 ± 1.1%, BMI mean 27.0 ± 4.4 kg/m²). A number of parametric associations were observed between a stronger rhythm, better objective sleep-wake characteristics, and less daytime sleepiness. Nonparametric circadian parameters were significantly associated with several outcomes: a stronger rhythm adherence (higher inter-daily stability) with better objective sleep-wake characteristics, better executive function, lower diabetes distress, less hyperglycemia risk, and more time spent in hypoglycemia/hypoglycemia risk; and a more robust rhythm (higher relative amplitude) with better objective sleep-wake characteristics and more time spent in hypoglycemia/higher hypoglycemia risk. Future work should be directed at designs that test causality, such as interventions directed at the strength and stability of rest-activity rhythms, for the potential to improve glucoregulation and other diabetes outcomes.