Therapeutics for Circadian Rhythm Sleep Disorders

Selecting, implementing and evaluating control and placebo conditions in light therapy and light-based interventions

Introduction: Light profoundly influences human physiology, behaviour and cognition by affecting various functions through light-sensitive cells in the retina. Light therapy has proven effective in treating seasonal depression and other disorders. However, designing appropriate control conditions for light-based interventions remains a challenge.Materials and methods: This article presents a novel framework for selecting, implementing and evaluating control conditions in light studies, offering theoretical foundations and practical guidance. It reviews the fundamentals of photoreception and discusses control strategies such as dim light, darkness, different wavelengths, spectral composition and metameric conditions. Special cases like dynamic lighting, simulated dawn and dusk, complex interventions and studies involving blind or visually impaired patients are also considered.Results: The practical guide outlines steps for selection, implementation, evaluation and reporting, emphasizing the importance of α-opic calculations and physiological validation.Conclusion: In conclusion, constructing effective control conditions is crucial for demonstrating the efficacy of light interventions in various research scenarios.

Midpoint of sleep is associated with sleep quality in older adults with and without symptomatic Alzheimer's disease

Introduction

Disrupted sleep is common in individuals with Alzheimer's disease (AD) and may be a marker for AD risk. The timing of sleep affects sleep-wake activity and is also associated with AD, but little is known about links between sleep architecture and the midpoint of sleep in older adults. In this study, we tested if the midpoint of sleep is associated with different measures of sleep architecture, AD biomarkers, and cognitive status among older adults with and without symptomatic AD.

Methods

Participants (N = 243) with a mean age of 74 underwent standardized cognitive assessments, measurement of CSF AD biomarkers, and sleep monitoring via single-channel EEG, actigraphy, a home sleep apnea test, and self-reported sleep logs. The midpoint of sleep was defined by actigraphy.

Results

A later midpoint of sleep was associated with African-American race and greater night-to-night variability in the sleep midpoint. After adjusting for multiple potential confounding factors, a later sleep midpoint was associated with longer rapid-eye movement (REM) onset latency, decreased REM sleep time, more actigraphic awakenings at night, and higher < 2 Hz non-REM slow-wave activity.

Conclusions

Noninvasive in vivo markers of brain function, such as sleep, are needed to track both future risk of cognitive impairment and response to interventions in older adults at risk for AD. Sleep timing is associated with multiple other sleep measures and may affect their utility as markers of AD. The midpoint of sleep may be changed through behavioral intervention and should be taken into account when using sleep as a marker for AD risk.

Prediction of dementia based on older adults' sleep disturbances using machine learning

BACKGROUND

The most common degenerative condition in older adults is dementia, which can be predicted using a number of indicators and whose progression can be slowed down. One of the indicators of an increased risk of dementia is sleep disturbances. This study aims to examine if machine learning can predict dementia and which sleep disturbance factors impact dementia.

METHODS

This study uses five machine learning algorithms (gradient boosting, logistic regression, gaussian naive Bayes, random forest and support vector machine) and data on the older population (60+) in Sweden from the Swedish National Study on Ageing and Care - Blekinge (n=4175). Each algorithm uses 10-fold stratified cross-validation to obtain the results, which consist of the Brier score for checking accuracy and the feature importance for examining the factors which impact dementia. The algorithms use 16 features which are on personal and sleep disturbance factors.

RESULTS

Logistic regression found an association between dementia and sleep disturbances. However, it is slight for the features in the study. Gradient boosting was the most accurate algorithm with 92.9% accuracy, 0.926 f1-score, 0.974 ROC AUC and 0.056 Brier score. The significant factors were different in each machine learning algorithm. If the person sleeps more than two hours during the day, their sex, education level, age, waking up during the night and if the person snores are the variables that most consistently have the highest feature importance in all algorithms.

CONCLUSION

There is an association between sleep disturbances and dementia, which machine learning algorithms can predict. Furthermore, the risk factors for dementia are different across the algorithms, but sleep disturbances can predict dementia.

Circadian rhythms and mood disorders: Time to see the light

The importance of time is ever prevalent in our world, and disruptions to the normal light/dark and sleep/wake cycle have now become the norm rather than the exception for a large part of it. All mood disorders, including seasonal affective disorder (SAD), major depressive disorder (MDD), and bipolar disorder (BD), are strongly associated with abnormal sleep and circadian rhythms in a variety of physiological processes. Environmental disruptions to normal sleep/wake patterns, light/dark changes, and seasonal changes can precipitate episodes. Moreover, treatments that target the circadian system have proven to be therapeutic in certain cases. This review will summarize much of our current knowledge of how these disorders associate with specific circadian phenotypes, as well as the neuronal mechanisms that link the circadian clock with mood regulation. We also discuss what has been learned from therapies that target circadian rhythms and how we may use current knowledge to develop more individually designed treatments.

Pharmacists' perspectives and attitudes towards the 2021 down-scheduling of melatonin in Australia using the Theoretical Domains Framework: a mixed-methods study

BACKGROUND

In Australia, prescription melatonin became a 'Pharmacist Only Medicine' for people over 55 with insomnia from June 2021. However, little is known about pharmacists' views on melatonin down-scheduling and perceived impacts on practice.

AIM

To explore Australian community pharmacists' views on and attitudes towards the down-scheduling of melatonin.

METHOD

A convenience sample of community pharmacists and pharmacy interns were recruited. Participants completed a survey capturing demographic and professional practice details, and rated their knowledge, beliefs and attitudes towards melatonin. This was followed by an online semi-structured interview. Interviews were guided by a schedule of questions developed using the Theoretical Domains Framework and explored the perceived role of melatonin, preparation/response to down-scheduling, practice changes and patient interactions. Interviews continued until data saturation and were digitally recorded, transcribed verbatim and analysed using the Framework Approach.

RESULTS

Twenty-four interviews were conducted with community pharmacists (n = 19) and intern pharmacists (n = 5), all practicing in metropolitan areas. Pharmacists/intern pharmacists welcomed the increased accessibility of melatonin for patients. However, pharmacists perceived a disconnect between the guidelines, supply protocols and pack sizes with practice, making it difficult to monitor patient use of melatonin. The miscommunication of eligibility also contributed to patient-pharmacist tension when supply was denied. Importantly, most participants indicated their interest in upskilling their knowledge in melatonin use in sleep, specifically formulation differences and dosage titration.

CONCLUSION

While pharmacists welcomed the down-scheduling of melatonin, several challenges were noted, contributing to pharmacist-patient tensions in practice. Findings highlight the need to refine and unify melatonin supply protocols and amend pack sizes to reflect guideline recommendations as well as better educating the public about the risk-benefits of melatonin.

Chronotype is Associated with Sleep Quality in Older Adults

Introduction

Disrupted sleep is common in individuals with Alzheimer's disease (AD) and may be a marker for AD risk. The timing of sleep or chronotype affects sleep-wake activity and is also associated with AD, but little is known about links between sleep and chronotype in older adults. In this study, we tested if different measures of sleep and chronotype are associated among older adults even after adjusting for multiple potentially confounding variables.

Methods

Participants (N=243) with a mean age of 74 underwent standardized cognitive assessments, measurement of CSF AD biomarkers, and sleep monitoring via single-channel EEG, actigraphy, and self-reported sleep logs. Chronotype was defined as the midpoint of sleep measured by actigraphy.

Results

Later mid-point of sleep (i.e., late chronotype) was associated with African American race and greater night-to-night variability in the sleep mid-point. After controlling for age, race, sex, cognitive status, AD biomarkers, and sleep disorders, a later mid-point of sleep was associated with longer rapid eye movement (REM) onset latency, decreased REM sleep time, lower sleep efficiency, increased sleep onset latency, and more awakenings at night. Late chronotype was also associated with increased <2 Hz non-REM slow-wave activity.

Conclusions

To identify individuals at risk for cognitive impairment before symptoms onset, non-invasive in vivo markers of brain function, such as sleep, are needed to track both future risk of cognitive impairment and response to interventions. Chronotype is a potential modifiable AD risk factor and should also be taken into account when using sleep as a marker for AD risk.

Updates and confounding factors in delayed sleep-wake phase disorder

Delayed sleep-wake phase disorder (DSWPD) is a circadian rhythm sleep disorder characterised by a delay in the main sleep period, with patients experiencing difficulty getting to sleep and waking up at socially appropriate times. This often causes insomnia and compromised sleep, results in impairment to daytime function and is associated with a range of comorbidities. Besides interventions aimed at ameliorating symptoms, there is good evidence supporting successful phase advancement with bright light therapy or melatonin administration. However, no treatment to date addresses the tendency to phase delay, which is a common factor amongst the various contributing causes of DSWPD. Circadian phase markers such as core body temperature and circulating melatonin typically correlate well with sleep timing in healthy patients, but numerous variations exist in DSWPD patients that can make these unpredictable for use in diagnostics. There is also increasing evidence that, on top of problems with the circadian cycle, sleep homeostatic processes actually differ in DSWPD patients compared to controls. This naturally has ramifications for management but also for the current approach to the pathogenesis itself in which DSWPD is considered a purely circadian disorder. This review collates what is known on the causes and treatments of DSWPD, addresses the pitfalls in diagnosis and discusses the implications of current data on modified sleep homeostasis, making clinical recommendations and directing future research.

Sleep Disturbance in Tourette's Disorder: Potential Underlying Mechanisms

Purpose of review

Sleep disturbance is common in TD. However, our understanding of the pathophysiological mechanisms involved is preliminary. This review summarizes findings from neuroimaging, genetic, and animal studies to elucidate potential underlying mechanisms of sleep disruption in TD.

Recent findings

Preliminary neuroimaging research indicates increased activity in the premotor cortex, and decreased activity in the prefrontal cortex is associated with NREM sleep in TD. Striatal dopamine exhibits a circadian rhythm; and is influenced by the suprachiasmatic nucleus via multiple molecular mechanisms. Conversely, dopamine receptors regulate circadian function and striatal expression of circadian genes. The association of TD with restless legs syndrome and periodic limb movements indicates shared pathophysiology, including iron deficiency, and variants in the BTDB9 gene. A mutations in the L-Histidine Decarboxylase gene in TD, suggests the involvement of the histaminergic system, implicated in arousal, in TD.

Summary

These biological markers have implications for application of novel, targeted interventions, including noninvasive neuromodulation, iron supplementation, histamine receptor antagonists, and circadian-based therapies for tic symptoms and/or sleep and circadian rhythms in TD.

Sleep intervention and glycemic control in gestational diabetes mellitus: a feasibility study

BACKGROUND

Over 50% of pregnant people report poor sleep quality and insomnia, with approximately 25% reporting short sleep (<7 hours per night). Short sleep duration is associated with impaired glucose functioning, insulin resistance, and type 2 diabetes mellitus. Although short sleep is associated with elevated blood glucose in patients with gestational diabetes mellitus, it is not known whether education on healthy sleep habits during pregnancy can improve sleep and thus glycemic control in these patients.

OBJECTIVE

We developed a sleep education program specific to pregnancy and targeted to patients with gestational diabetes mellitus. We aimed to evaluate the feasibility of this intervention in the setting of a randomized controlled trial.

STUDY DESIGN

A sleep education program specific to pregnancy, "Sleep-4-2," was developed via multidisciplinary collaboration between specialists in maternal-fetal medicine, sleep medicine, and psychiatry. The program was presented to focus groups of pregnant people and a separate group of healthcare providers to gauge acceptability of the program and to modify content. This program was then tested on a group of patients diagnosed with gestational diabetes mellitus. Participants were randomized to a group receiving standard gestational diabetes mellitus care or a group participating in the sleep education program. Baseline demographics, sleep knowledge, and self-reported sleep quality information were obtained from all participants at enrollment and again at 35 weeks of pregnancy. Change in sleep knowledge and quality and degree of glycemic control were compared between groups.

RESULTS

Between December 2017 and July 2019, 140 patients were screened and 74 were enrolled in the study and randomized. Recruitment to the study was acceptable, with >50% of eligible approached patients agreeing to participate, and retention in the intervention group was high at 94%. We did not demonstrate any difference in sleep knowledge or in the proportion of patients achieving glycemic control during pregnancy.

CONCLUSION

Implementation of a sleep education program specific to pregnancy for patients with gestational diabetes mellitus was feasible in the context of typical care. A definitive trial could be developed on the basis of this pilot study to evaluate whether a sleep intervention in pregnancy can improve glycemic control in patients with gestational diabetes mellitus.

A circadian clock translational control mechanism targets specific mRNAs to cytoplasmic messenger ribonucleoprotein granules

Phosphorylation of Neurospora crassa eukaryotic initiation factor 2 α (eIF2α), a conserved translation initiation factor, is clock controlled. To determine the impact of rhythmic eIF2α phosphorylation on translation, we performed temporal ribosome profiling and RNA sequencing (RNA-seq) in wild-type (WT), clock mutant Δfrq, eIF2α kinase mutant Δcpc-3, and constitutively active cpc-3c cells. About 14% of mRNAs are rhythmically translated in WT cells, and translation rhythms for ∼30% of these mRNAs, which we named circadian translation-initiation-controlled genes (cTICs), are dependent on the clock and CPC-3. Most cTICs are expressed from arrhythmic mRNAs and contain a P-body (PB) localization motif in their 5' leader sequence. Deletion of SNR-1, a component of cytoplasmic messenger ribonucleoprotein granules (cmRNPgs) that include PBs and stress granules (SGs), and the PB motif on one of the cTIC mRNAs, zip-1, significantly alters zip-1 rhythmic translation. These results reveal that the clock regulates rhythmic translation of specific mRNAs through rhythmic eIF2α activity and cmRNPg metabolism.

Circadian dysregulation and Alzheimer’s disease: A comprehensive review

Alzheimer’s disease (AD), the foremost variant of dementia, has been associated with a menagerie of risk factors, many of which are considered to be modifiable. Among these modifiable risk factors is circadian rhythm, the chronobiological system that regulates sleep‐wake cycles, food consumption timing, hydration timing, and immune responses amongst many other necessary physiological processes. Circadian rhythm at the level of the suprachiasmatic nucleus (SCN), is tightly regulated in the human body by a host of biomolecular substances, principally the hormones melatonin, cortisol, and serotonin. In addition, photic information projected along afferent pathways to the SCN and peripheral oscillators regulates the synthesis of these hormones and mediates the manner in which they act on the SCN and its substructures. Dysregulation of this cycle, whether induced by environmental changes involving irregular exposure to light, or through endogenous pathology, will have a negative impact on immune system optimization and will heighten the deposition of Aβ and the hyperphosphorylation of the tau protein. Given these correlations, it appears that there is a physiologic association between circadian rhythm dysregulation and AD. This review will explore the physiology of circadian dysregulation in the AD brain, and will propose a basic model for its role in AD‐typical pathology, derived from the literature compiled and referenced throughout.

Adjunctive bright light treatment with gradual advance in unipolar major depressive disorder with evening chronotype - A randomized controlled trial

BACKGROUND

Unipolar non-seasonal depressed patients with concomitant evening chronotype were associated with poor clinical outcomes and higher non-remission rate. This study aims to examine the efficacy of adjunctive bright light therapy with gradual timing advance in a randomized, assessor and prescriber-blinded controlled trial.

METHOD

Participants were randomly allocated to receive 5 weeks of either bright white light therapy (BLT) or dim red light (DRL) with the same advancement protocol. Participants were followed up till 5 months after treatment. Primary outcomes included (i) remission rate and (ii) the severity of depression. The analysis was conducted using Kaplan-Meier survival analysis, Cox proportional hazard analysis and linear mixed models.

RESULTS

A total of 93 participants (46.4 ± 11.7 years old, 80% female) were randomized. The cumulative remission rate for the BLT and the DRL groups was 67.4% and 46.7%, respectively. Time to remission was shorter for the BLT group relative to the DRL group (log-rank test p = 0.024). Cox proportional hazard survival analysis showed that patients in the BLT group had a higher probability of achieving remission relative to patients in the DRL group [hazard ratio = 1.9 (95% CI = 1.1- 3.4), p = 0.026]. Further sensitivity analysis demonstrated greater improvement in 17-Hamilton Depression Score (group × time interaction, p = 0.04) in the BLT group for those who were adherent to light therapy.

CONCLUSIONS

The use of bright light therapy with gradual advance protocol is an effective adjunctive treatment resulting in quicker and a higher rate of remission of depression in patients with non-seasonal unipolar depression and evening-chronotype.

Static postural stability and neuropsychological performance after awakening from REM and NREM sleep in patients with chronic insomnia: a randomized, crossover, overnight polysomnography study

STUDY OBJECTIVES

Chronic insomnia disorder (CID) is a common sleep disorder, with a prevalence ranging from 6% to 10% worldwide. Individuals with CID experience more fragmented sleep than healthy controls do. They awaken frequently during the night and have a higher risk of injury from falling. Awakening from different sleep stages may have different effects on postural stability and waking performance. However, limited research has been conducted on this topic.

METHODS

This prospective randomized crossover study was conducted between January 2015 and January 2017. We included 20 adults aged 20-65 years who fulfilled diagnosis criteria for CID. Participants underwent two overnight polysomnography studies with an interval of at least 7 days. They were awakened during either rapid eye movement (REM) sleep or N1/N2 sleep alternatively. We compared measurements of static postural stability, vigilance scores, and neuropsychological tests between REM and N1/N2 sleep awakening.

RESULTS

Polysomnography parameters between the two nights were comparable. Participants who were awakened from REM sleep had worse static postural stability than those with N1/N2 awakening. Compared with N1/N2 awakening, larger mean sway areas of center of pressure (COP; p = 0.0413) and longer COP mean distances (p = 0.0139) were found in REM sleep awakening. There were no statistically significant differences in vigilance scores or neuropsychological tests between the two nights.

CONCLUSIONS

REM sleep awakening was associated with worse static postural stability than was N1/N2 awakening. No statistically significant differences were found in waking performance in alertness or in neuropsychological tests between N1/N2 and REM sleep awakening.

2022 Prevention of chronic non-communicable diseases in Of the Russian Federation. National guidelines

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Effects of different light incident angles via a head-mounted device on the magnitude of nocturnal melatonin suppression in healthy young subjects

Bright light is a primary zeitgeber (synchronizer) for the central circadian pacemaker in humans. Recently, head-mounted devices for light therapy have been developed to treat patients suffering from circadian rhythm sleep disorders. In this study, to evaluate the influence of the light incident angle of head-mounted devices on the human circadian pacemaker, we examined the effects of bright light (ca.10000 lx) from two different angles (55° vs. 28°) on the suppression of melatonin secretion at night. Twenty-nine subjects (25.1 ± 6.3 SD years) participated in the present study. The subjects were kept under dim light conditions (< 5 lx) from 4 h before their habitual bedtime, followed by exposure to 1 h of bright light at two different angles during their habitual bedtime. Saliva samples were collected every hour under dim light conditions and then collected every 30 min during the bright light exposure. To assess the effect of the light incident angle on ipRGCs mediating light-evoked pupillary constriction, pupil size was measured in before and after exposure to bright light. Melatonin suppression in the group exposed to light at 28° was significantly higher than that in the group with light at 55° (p < 0.001). The pupillary constriction was significantly greater in the group exposed to light at 28° than that in the group with light at 55° (p < 0.001). The present findings suggest that the light incident angle is an important factor for bright light therapy and should be considered to effectively use head-mounted devices in home and clinical settings.

Impact of sleep patterns upon female neuroendocrinology and reproductive outcomes: a comprehensive review

Sleep is vital to human bodily function. Growing evidence indicates that sleep deprivation, disruption, dysrhythmia, and disorders are associated with impaired reproductive function and poor clinical outcomes in women. These associations are largely mediated by molecular-genetic and hormonal pathways, which are crucial for the complex and time sensitive processes of hormone synthesis/secretion, folliculogenesis, ovulation, fertilization, implantation, and menstruation. Pathologic sleep patterns are closely linked to menstrual irregularity, polycystic ovarian syndrome, premature ovarian insufficiency, sub/infertility, and early pregnancy loss. Measures of success with assisted reproductive technology are also lower among women who engage in shift work, or experience sleep disruption or short sleep duration. Extremes of sleep duration, poor sleep quality, sleep disordered breathing, and shift work are also associated with several harmful conditions in pregnancy, including gestational diabetes and hypertensive disorders. While accumulating evidence implicates pathologic sleep patterns in impaired reproductive function and poor reproductive outcomes, additional research is needed to determine causality and propose therapeutic interventions.

Morning light therapy in adults with Tourette's disorder

BACKGROUND

Sleep disturbance is common among individuals with Tourette's Disorder (TD). Given that sleep is influenced by the circadian system, this study examined circadian rhythms and sleep in adults with TD, and explored the possible benefit of short-wavelength wearable morning light therapy.

METHODS

Participants were 34 adults with TD (n = 14) and age- and sex-matched healthy controls (HC; n = 20). Participants were screened using clinician-rated diagnostic and tic severity interviews, and procedures lasted 3 consecutive weeks. Participants completed a baseline week of actigraphy. Adults with TD completed 2 weeks of Re-Timer™ morning light therapy and continued actigraphy monitoring. Dim light melatonin-onset (DLMO) phase assessment, tic severity interview, and measures of chronotype, sleep disturbance, daytime sleepiness, disability, depression, anxiety, and stress were completed at baseline and post-intervention.

RESULTS

Adults with TD reported significantly greater eveningness and sleep disturbance relative to controls. Per wrist actigraphy, adults with TD exhibited significantly longer sleep-onset latency, lower sleep efficiency, and greater sleep fragmentation than HC. Following morning light therapy, there was a significant advance in DLMO phase, but not self-report or actigraphy sleep variables. There were small, statistically significant decreases in tic severity and impairment. There were also significant reductions in daytime sleepiness, and self-reported anxiety, but not depression, stress, or disability. Participants reported minimal side effects and rated light therapy as acceptable and comfortable.

CONCLUSIONS

Findings showed some benefits following brief light therapy in TD; further exploration of the impact of spectral tuning the photic environment as part of treatment for TD subjects is warranted.

New and Emerging Approaches to Better Define Sleep Disruption and Its Consequences

Current approaches to quantify and diagnose sleep disorders and circadian rhythm disruption are imprecise, laborious, and often do not relate well to key clinical and health outcomes. Newer emerging approaches that aim to overcome the practical and technical constraints of current sleep metrics have considerable potential to better explain sleep disorder pathophysiology and thus to more precisely align diagnostic, treatment and management approaches to underlying pathology. These include more fine-grained and continuous EEG signal feature detection and novel oxygenation metrics to better encapsulate hypoxia duration, frequency, and magnitude readily possible via more advanced data acquisition and scoring algorithm approaches. Recent technological advances may also soon facilitate simple assessment of circadian rhythm physiology at home to enable sleep disorder diagnostics even for “non-circadian rhythm” sleep disorders, such as chronic insomnia and sleep apnea, which in many cases also include a circadian disruption component. Bringing these novel approaches into the clinic and the home settings should be a priority for the field. Modern sleep tracking technology can also further facilitate the transition of sleep diagnostics from the laboratory to the home, where environmental factors such as noise and light could usefully inform clinical decision-making. The “endpoint” of these new and emerging assessments will be better targeted therapies that directly address underlying sleep disorder pathophysiology via an individualized, precision medicine approach. This review outlines the current state-of-the-art in sleep and circadian monitoring and diagnostics and covers several new and emerging approaches to better define sleep disruption and its consequences.

Light Therapy for QoL/Depression in AYA With Cancer: A Randomized Trial

OBJECTIVE

Secondary outcomes from a published feasibility and acceptability trial were examined to explore the effect of bright white light (BWL) on quality of life (QoL) and depressive symptoms compared to dim red light (DRL) control in adolescents and young adults (AYAs) receiving cancer-directed therapy.

METHODS

Fifty-one AYAs (12-22 years, 51% male) newly diagnosed with cancer were randomized to receive 8 weeks of BWL (n = 26) or DRL (n = 25). The CDI-2 (total score, negative mood/physical symptoms, interpersonal problems, ineffectiveness, and negative self-esteem) and parent- and self-report PedsQL (total score and subscales of physical, emotional, social, and school QoL) were completed at multiple timepoints.

RESULTS

BWL produced improvements in self-reported total depression (d = -.64; 95% confidence interval [CI] = -1.26, -0.01), negative self-esteem (d = -.80; 95% CI = -1.43, -.14), negative mood/physical symptoms (d = -.73; 95% CI = -1.36, -0.08), ineffectiveness (d = -.43; 95% CI = -1.04, .19), total self-reported QoL (d = .41; 95% CI = -.16, .96), emotional (d = .78; 95% CI = .19, 1.37), school functioning (d = .48; 95% CI = -.09, 1.04), and parent-reported school functioning (d = .66; 95% CI = 0.02, 1.33). BWL reported a greater rate of improvement than DRL for total depression (β = .49, p < .05) and self-esteem (β = .44, p < .05), and parent-reported school functioning (β = -1.68, p < .05).

CONCLUSIONS

BWL improved QoL and depressive symptoms for AYAs with cancer. These findings will inform larger randomized controlled trials.

Structure-based design and classifications of small molecules regulating the circadian rhythm period

Circadian rhythm is an important mechanism that controls behavior and biochemical events based on 24 h rhythmicity. Ample evidence indicates disturbance of this mechanism is associated with different diseases such as cancer, mood disorders, and familial delayed phase sleep disorder. Therefore, drug discovery studies have been initiated using high throughput screening. Recently the crystal structures of core clock proteins (CLOCK/BMAL1, Cryptochromes (CRY), Periods), responsible for generating circadian rhythm, have been solved. Availability of structures makes amenable core clock proteins to design molecules regulating their activity by using in silico approaches. In addition to that, the implementation of classification features of molecules based on their toxicity and activity will improve the accuracy of the drug discovery process. Here, we identified 171 molecules that target functional domains of a core clock protein, CRY1, using structure-based drug design methods. We experimentally determined that 115 molecules were nontoxic, and 21 molecules significantly lengthened the period of circadian rhythm in U2OS cells. We then performed a machine learning study to classify these molecules for identifying features that make them toxic and lengthen the circadian period. Decision tree classifiers (DTC) identified 13 molecular descriptors, which predict the toxicity of molecules with a mean accuracy of 79.53% using tenfold cross-validation. Gradient boosting classifiers (XGBC) identified 10 molecular descriptors that predict and increase in the circadian period length with a mean accuracy of 86.56% with tenfold cross-validation. Our results suggested that these features can be used in QSAR studies to design novel nontoxic molecules that exhibit period lengthening activity.

The Effect of Bright Light Treatment on Rest-Activity Rhythms in People with Dementia: A 24-Week Cluster Randomized Controlled Trial

Bright light treatment is an effective way to influence circadian rhythms in healthy adults, but previous research with dementia patients has yielded mixed results. The present study presents a primary outcome of the DEM.LIGHT trial, a 24-week randomized controlled trial conducted at nursing homes in Bergen, Norway, investigating the effects of a bright light intervention. The intervention consisted of ceiling-mounted LED panels providing varying illuminance and correlated color temperature throughout the day, with a peak of 1000 lx, 6000 K between 10 a.m. and 3 p.m. Activity was recorded using actigraphs at baseline and after 8, 16, and 24 weeks. Non-parametric indicators and extended cosine models were used to investigate rest-activity rhythms, and outcomes were analyzed with multi-level regression models. Sixty-one patients with severe dementia (median MMSE = 4) were included. After 16 weeks, the acrophase was advanced from baseline in the intervention group compared to the control group (B = -1.02, 95%; CI = -2.00, -0.05). There was no significant difference between the groups on any other rest-activity measures. When comparing parametric and non-parametric indicators of rest-activity rhythms, 25 out of 35 comparisons were significantly correlated. The present results indicate that ambient bright light treatment did not improve rest-activity rhythms for people with dementia.

Feasibility and Acceptability of Light Therapy to Reduce Fatigue in Adolescents and Young Adults Receiving Cancer-Directed Therapy

OBJECTIVE/BACKGROUND

Fatigue is one of the most consistent and distressing symptoms reported by adolescent/young adult (AYA) oncology patients. Bright white light (BWL) is used to treat fatigue in adult oncology but has not been explored in AYA oncology patients. The purpose of the current study was to determine the feasibility and acceptability of BWL for AYA who were receiving cancer-directed therapy.

PARTICIPANTS

51 AYA patients with newly diagnosed solid tumors, including lymphoma.

METHODS

Participants were randomized to dim red light (DRL, n = 25) or BWL (n = 26) from devices retrofitted with adherence monitors for 30 minutes upon awakening daily for 8 weeks. Side effects were assessed via modified Systematic Assessment for Treatment-Emergent Effects (SAFTEE). Participants completed the PedsQL Multidimensional Fatigue Scale.

RESULTS

Of patients approached, 73% consented and participated. Mean adherence was 57% of days on study with 30.68 average daily minutes of usage. BWL did not cause more extreme treatment-emergent effects over DRL. Patients in the BWL group demonstrated significant improvement on all fatigue outcomes by both self-report and parent proxy report, which was not observed in the DRL group.

CONCLUSIONS

This is the first study to evaluate the feasibility and acceptability of light therapy to reduce fatigue in AYA patients receiving cancer-directed therapy. These findings demonstrate the feasibility and acceptability of the intervention and provide preliminary evidence of the potential benefits of BWL, which warrants further study in a confirmatory efficacy trial.ClinicalTrials.gov Identifier Number: NCT02429063.

Sleep disturbances and cognitive impairment in schizophrenia spectrum disorders: a systematic review and narrative synthesis

Individuals with schizophrenia spectrum disorders (SSD) experience frequent sleep disturbances in addition to enduring cognitive impairments. The purpose of the present review was to systematically summarise our current understanding of the association between sleep disturbances and cognition in SSD. Through this, it was aimed to identify features of disturbed sleep that are reliably associated with cognitive deficits in SSD and identify the gaps within the current literature that require future investigation. Eighteen relevant studies were identified following a two-stage screening process. Following a structured narrative synthesis of key study components, no clear and consistent pattern emerged. Considerable methodological variability was present amongst the reviewed studies. Although some broad consistencies were identified, such as associations between sleep spindle density and sleep-dependent memory consolidation, the overall pattern of results lacked a cohesive composition due to the diverse list of sleep parameters and cognitive domains investigated, as well as a lack of replication. Additional research is needed before more definitive remarks can be made regarding the influence of sleep disturbances on cognitive function in SSD.

Positive effect of timed blue-enriched white light on sleep and cognition in patients with mild and moderate Alzheimer's disease

Conflicting results have been reported regarding the effectiveness of light treatment (LT) in patients with Alzheimer's disease (AD). We investigated the effectiveness of blue-enriched white LT on sleep, cognition, mood and behavior in patients with mild and moderate AD. The treatment group (n = 14) sat about 60 cm away from a small (136 × 73 × 16 mm) LED light box for 1 h each morning for 2 weeks. The control group (n = 11) wore dark, blue-attenuating sunglasses during the 1 h exposures. The morning light started 9-10 h after each individual's dim light melatonin onset (DLMO). Assessments were done at baseline (T0), immediate post-treatment (T1), and 4 weeks after the end of the 2 weeks of LT (T2). Sleep was measured by actigraphy. Blue-enriched LT had a significantly better effect on the Pittsburgh Sleep Quality Index at T2 compared to blue-attenuated LT, and a trend of better effectiveness on total sleep time at T2. There was a significant increase in Mini-Mental State Examination score at T2 after blue-enriched LT than that at T0. Our findings suggest that morning blue-enriched LT has a benefit in improving sleep and cognitive function in AD patients.

Melatonin and its mechanism of action in the female reproductive system and related malignancies

Melatonin (N-acetyl-5-methoxytryptamine), the main product of pineal gland in vertebrates, is well known for its multifunctional role which has great influences on the reproductive system. Recent studies documented that melatonin is a powerful free radical scavenger that affects the reproductive system function and female infertility by MT1 and MT2 receptors. Furthermore, cancer researches indicate the influence of melatonin on the modulation of tumor cell signaling pathways resulting in growth inhibitor of the both in vivo/in vitro models. Cancer adjuvant therapy can also benefit from melatonin through therapeutic impact and decreasing the side effects of radiation and chemotherapy. This article reviews the scientific evidence about the influence of melatonin and its mechanism of action on the fertility potential, physiological alteration, and anticancer efficacy, during experimental and clinical studies.

Sleep and Metabolic Syndrome

Metabolic syndrome (MetS) refers to the clustering of risk factors for cardiovascular disease and diabetes, including central adiposity, hypertension, dyslipidemia, and hyperglycemia. During the past 20 years, there have been parallel and epidemic increases in MetS and impaired sleep. This article describes evidence on the association between MetS and short sleep duration, circadian misalignment, insomnia, and sleep apnea. Potential mechanisms where impaired sleep desynchronizes and worsens metabolic control and interventions to improve sleep and potentially improve MetS are presented.

Pharmacokinetics of exogenous melatonin in relation to formulation, and effects on sleep: A systematic review

There is conflicting evidence on the clinical efficacy of exogenous melatonin for the treatment of sleep disorders. This may be due to differences in the pharmacokinetic (PK) properties of melatonin formulations used in clinical trials. The aim of this systematic review was to understand the relationship between melatonin formulations and PK parameters and, where possible, the effects on sleep outcomes. To this purpose, we conducted a systematic review and nineteen papers were included. The studies included three melatonin transdermal formulation, thirteen oral formulations, one topical, two buccal, two intravenous and two nasogastric formulations. Seven studies investigated the effect of the melatonin formulation on sleep and six of them found a significant improvement in one or more sleep parameters. The potential for an improved controlled release formulation that delays maximum concentration (C_max) was identified. The different formulations and doses affect melatonin PK, suggesting that treatment efficacy maybe affected. Based on the current evidence, we are unable to provide recommendations of specific melatonin formulations and PK parameters for specific sleep disorders. Future studies should systematically investigate how different PK parameters of melatonin formulations affect efficacy treatment of sleep as well as circadian disorders.

Sleep interventions and glucose metabolism: systematic review and meta-analysis

OBJECTIVE

Sleep disturbances (insufficient or poor sleep quality) have been linked to abnormal glucose metabolism. This systematic review and meta-analysis aimed to explore the effects of behavioral and pharmacological sleep interventions on glucose metabolism.

METHODS

Medline and Embase were used for systematic search. Studies reporting behavioral or pharmacological interventions in population with sleep disturbances, with measured outcomes of glucose metabolism and sleep parameters were selected.

RESULTS

Twenty two studies were eligible for review (eight were conducted in people with type 2 diabetes). Studies were grouped into three types of intervention: sleep extension (n = 6), sleep education or cognitive behavioral therapy for insomnia (CBT-I, n = 6) and pharmacological interventions (n = 10). CBT-I and sleep education resulted in significantly improved self-reported sleep quality (Pittsburgh Sleep Quality Index, mean difference, MD, -1.31, 95% confidence interval (CI) -1.83, -0.80), non-significant reduction in hemoglobin A1c level (MD -0.35%, 95% CI -0.84, 0.13), and non-significant reduction in fasting glucose levels (MD -4.76 mg/dL, 95% CI -14.19, 4.67). Other studies were not eligible for meta-analysis due to heterogeneity of interventions or outcomes. Sleep extension was able to increase sleep duration by varying degrees in short sleepers, and five of six studies demonstrated relationships between the intervention and measures of insulin resistance. A majority of pharmacological intervention studies showed improved sleep but the effects on glucose metabolism were mixed.

CONCLUSIONS

Available sleep interventions were effective in improving sleep but the effects on glucose metabolism were inconclusive. Larger randomized studies with consistent outcome measurements are needed to demonstrate this potential causal relationship.

Memory and the circadian system: Identifying candidate mechanisms by which local clocks in the brain may regulate synaptic plasticity

The circadian system is an endogenous biological network responsible for coordinating near-24-h cycles in behavior and physiology with daily timing cues from the external environment. In this review, we explore how the circadian system regulates memory formation, retention, and recall. Circadian rhythms in these memory processes may arise through several endogenous pathways, and recent work highlights the importance of genetic timekeepers found locally within tissues, called local clocks. We evaluate the circadian memory literature for evidence of local clock involvement in memory, identifying potential nodes for direct interactions between local clock components and mechanisms of synaptic plasticity. Our discussion illustrates how local clocks may pervasively modulate neuronal plastic capacity, a phenomenon that we designate here as circadian metaplasticity. We suggest that this function of local clocks supports the temporal optimization of memory processes, illuminating the potential for circadian therapeutic strategies in the prevention and treatment of memory impairment.

Similarities of Aspects of Biological Rhythms between Major Depression and Bipolar II Disorder Compared to Bipolar I Disorder: A Finding from the Early-Onset Mood Disorder Cohort

OBJECTIVE

The biological rhythm is closely related to mood symptoms. The purpose of this study was to assess the differences in biological rhythms among subjects with mood disorder [bipolar I disorder (BD I), bipolar II disorder (BD II), major depressive disorder (MDD)] and healthy control subjects.

METHODS

A total of 462 early-onset mood disorder subjects were recruited from nine hospitals. The controls subjects were recruited from the general population of South Korea. Subject groups and control subject were evaluated for the Korean language version of Biological Rhythms Interview of Assessment in Neuropsychiatry (K-BRIAN) at the initial evaluation.

RESULTS

The mean K-BRIAN scores were 35.59 [standard deviation (SD)=13.37] for BD I, 43.05 (SD=11.85) for BD II, 43.55 (SD=12.22) for MDD, and 29.1 (SD=8.15) for the control group. In the case of mood disorders, biological rhythm disturbances were greater than that in the control group (p<0.05). A significant difference existed between BD I and BD II (BD I <BD II, p<0.001) and between BD I and MDD (BD I<MDD, p< 0.001) but no difference was observed between BD II and MDD.

CONCLUSION

BD II and MDD are similar to each other but different from BD I in biological rhythm patterns in early-onset mood disorder cases. Biological rhythm disturbances are similar for early-onset major depression and BD II.

Home versus laboratory assessments of melatonin production and melatonin onset in young adults complaining of a delayed sleep schedule

Recent evidence points toward an association between higher non-visual sensitivity to light and a later circadian phase in young adults complaining of a delayed sleep schedule. Light exposure in the evening may therefore induce a larger suppression of melatonin production in these individuals, which might: (a) bias home estimates of melatonin onset; and (b) decrease sleep propensity at bedtime. In this study, we compared home and laboratory melatonin onsets and production in sleep-delayed and control participants, using saliva samples collected in the 3 hr preceding habitual bedtime. The mean light intensity measured during saliva sampling at home was ~10 lux in both groups. Melatonin suppression at home was significant, averaging 31% and 24% in sleep-delayed and control individuals, respectively. Group difference in melatonin suppression was not significant. Estimates of melatonin onset were on average 27 min later at home than in laboratory conditions, with no group difference. Looking specifically at sleep-delayed participants, there was no correlation between non-visual sensitivity to light and home-laboratory differences in melatonin onsets. However, higher light sensitivity was associated with greater melatonin suppression in the hour before habitual bedtime. Greater melatonin suppression before bedtime was also associated with a later circadian phase. These results indicate that the validity of home estimates of melatonin onset is similar in sleep-delayed and in control individuals. Results also suggest that increased non-visual sensitivity to light could impact melatonin secretion in sleep-delayed individuals and contribute to a late bedtime by delaying circadian phase and decreasing sleep propensity.

The Impact of Sleep and Circadian Disorders on Physician Burnout

Nearly 50% of physicians report symptoms of clinical burnout. Occupational factors and personal health play substantial roles in physician burnout. The role of sleep in physician burnout is not well understood. Burnout is at epidemic levels in health care, with research suggesting nearly one in two physicians experience clinical burnout as defined according to the Maslach Burnout Index. Sleep deprivation, burnout, and clinician health are intricately intertwined. The relation between sleep deprivation and burnout is not only suggested in hypothetical models but also confirmed in observational studies of workers of all types. Models describing the relation between burnout and sleep suggest as potential causative mechanisms of sleep disturbances the following: (1) a chronic depletion of energy stores; or (2) activation of the hypothalamic-pituitary-adrenal axis and increasing levels of bodily stress. Sleep deprivation and burnout are widespread in health-care workers, affecting not only nurses but also medical students, physicians-in-training, and practicing physicians. Although sleep deprivation is associated with clinical burnout, direct studies showing that sleep extension can improve burnout recovery are lacking. Early detection and early intervention to improve both sleep deprivation and burnout are warranted in health-care professionals. Interventions should be directed not only at individuals but also at the entire health system. This review highlights the latest developments and emerging concepts concerning the role of sleep and circadian disorders in physician burnout.

Circadian Rhythmicity as a Predictor of Quality of Life in Allogeneic Hematopoietic Cell Transplant Patients

CONTEXT

Quality of life (QoL) is increasingly recognized as an important outcome of cancer treatment. Previous studies have examined clinical predictors of QoL, but with the increasing prevalence of wearable sensors that monitor sleep and activity patterns, further investigation into whether these behaviors are predictive of post-treatment QoL is now feasible. Among patients receiving aggressive cancer treatment such as hematopoietic cell transplantation (HCT), analysis of circadian rhythms (24-hour patterns of sleep and activity) via wearable sensors is limited.

OBJECTIVE

To evaluate the relationship between overall QoL and circadian rhythms in patients receiving allogeneic HCT.

METHODS

Patients wore an ActiGraph GT3X (Pensacola, FL) activity monitor for at least 72 hours before the initiation of conditioning chemotherapy and transplantation and completed a QoL (Functional Assessment of Cancer Therapy-General [FACT-G]) assessment. QoL assessments were also completed 1, 3, and 6 months after HCT.

RESULTS

Patients (n = 45, M age = 55) were mostly male (66%) with a total FACT-G score of 80.96 (SD = 16.05) before HCT. Mixed models revealed robust cross-sectional associations between overall QoL and multiple circadian rhythmicity parameters, including durations of high physical activity, overall circadian rhythmicity, and earlier starts of daily activity (P's < .01). Recovery of QoL after transplant was predicted by longer pre-transplant durations of high physical activity (P = .04) and earlier evening retirement (P = .04).

CONCLUSION

Our findings suggest that wearable sensor information is a promising method of predicting recovery of QoL after HCT. Additional studies are needed to confirm these findings in a larger sample.

Clinical neurophysiology of circadian rhythm sleep-wake disorders

Circadian rhythms are the endogenous near-24-h oscillations in physiologic processes. In mammals the suprachiasmatic nucleus serves as the primary circadian pacemaker, and it maintains rhythmicity at a genetic level through a complex transcription-translation feedback loop of core circadian clock genes. The circadian clock is entrained to the environment through daily exposure to light and melatonin. Disruption of these endogenous rhythms or the ability to entrain to the surrounding environment results in the circadian rhythm sleep-wake disorders (CRSWDs). Patients with CRSWDs can present with either late sleep/wake times (delayed sleep-wake phase disorder), early sleep/wake times (advanced sleep-wake phase disorder), inconsistent sleep/wake times (irregular sleep-wake rhythm disorder) or sleep-wake times that move progressively later each day (non-24-h sleep-wake rhythm disorder). Diagnosis of these disorders relies on the use of sleep logs and/or actigraphy to demonstrate the daily patterns of rest and activity. Treatment of the CRSWDs focuses on sleep hygiene and strategically timed light and melatonin.

More evening preference is positively associated with systemic inflammation in prediabetes and type 2 diabetes patients

Currently it is not known whether morningness-eveningness preference in non-night shift working population is associated with systemic inflammation. This study investigated the relationship between morningness-eveningness and systemic inflammation, as measured by high-sensitivity C-reactive protein (hs-CRP) in 163 non-night shift working patients with abnormal glucose tolerance (86 type 2 diabetes and 77 prediabetes). Morningness-eveningness was assessed by Composite Scale of Morningness, and participants were screened for Obstructive sleep apnea (OSA). Sleep duration, efficiency, and variability were obtained using actigraphy, and depressive symptoms and dietary patterns were also captured. Participants' mean age was 54.7 ± 10.4 years and median hs-CRP was 1.39 (interquartile range 0.82, 3.33) mg/L. More evening preference was significantly associated with higher natural log transformed (ln) hs-CRP (B = -0.051, p = 0.001). Diabetes status, glycemic control, OSA severity, sleep duration, caloric consumption and timing were not related to hs-CRP. After adjusting for age, sex, body mass index, depressive symptoms, sleep efficiency, sleep variability, percentage of daily caloric intake from protein, and statin use, more evening preference was independently associated with higher ln hs-CRP (B = -0.032, p = 0.014). In summary, in non-night shift working patients with abnormal glucose tolerance, more evening preference was independently associated with higher systemic inflammation. This finding underscore the importance of circadian regulation on cardiovascular health.

Melatonin prevents hypochlorous acid-mediated cyanocobalamin destruction and cyanogen chloride generation

Hypochlorous acid (HOCl) is a potent cytotoxic oxidant generated by the enzyme myeloperoxidase (MPO) in the presence of hydrogen peroxide (H₂ O₂ ) and chloride (Cl^- ). Elevated levels of HOCl play an important role in various pathological conditions through oxidative modification of several biomolecules. Recently, we have highlighted the ability of HOCl to mediate the destruction of the metal-ion derivatives of tetrapyrrole macrocyclic rings such as hemoproteins and vitamin B₁₂ (VB₁₂ ) derivatives. Destruction of cyanocobalamin, a common pharmacological form of VB₁₂ mediated by HOCl, results in the generation of toxic molecular products such as chlorinated derivatives, corrin ring cleavage products, the toxic blood agents cyanide (CN^- ) and cyanogen chloride (CNCl), and redox-active free cobalt. Here, we show that melatonin prevents HOCl-mediated cyanocobalamin destruction, using a combination of UV-Vis spectrophotometry, high-performance liquid chromatography analysis, and colorimetric CNCl assay. Identification of several melatonin oxidation products suggests that the protective role of melatonin against HOCl-mediated cyanocobalamin destruction and subsequent CNCl generation is at the expense of melatonin oxidation. Collectively, this work highlights that, in addition to acting as an antioxidant and as a MPO inhibitor, melatonin can also prevent VB₁₂ deficiency in inflammatory conditions such as cardiovascular and neurodegenerative diseases, among many others.

Quality of life, sleep and rheumatoid arthritis (QUASAR): a protocol for a prospective UK mHealth study to investigate the relationship between sleep and quality of life in adults with rheumatoid arthritis

INTRODUCTION

People with rheumatoid arthritis (RA) frequently report reduced health-related quality of life (HRQoL), the impact one's health has on physical, emotional and social well-being. There are likely numerous causes for poor HRQoL, but people with RA have identified sleep disturbances as a key contributor to their well-being. This study will identify sleep/wake rhythm-associated parameters that predict HRQoL in patients with RA.

METHODS AND ANALYSIS

This prospective cohort study will recruit 350 people with RA, aged 18 years or older. Following completion of a paper-based baseline questionnaire, participants will record data on 10 symptoms including pain, fatigue and mood two times a day for 30 days using a study-specific mobile application (app). A triaxial accelerometer will continuously record daytime activity and estimate evening sleep parameters over the 30 days. Every 10 days following study initiation, participants will complete a questionnaire that measures disease specific (Arthritis Impact Measurement Scale 2-Short Form (AIMS2-SF)) and generic (WHOQOL-BREF) quality of life. A final questionnaire will be completed at 60 days after entering the study. The primary outcomes are the AIMS2-SF and WHOQOL-BREF. Structural equation modelling and latent trajectory models will be used to examine the relationship between sleep/wake rhythm-associated parameters and HRQoL, over time.

ETHICS AND DISSEMINATION

Results from this study will be disseminated at regional and international conferences, in peer-reviewed journals and Patient and Public Engagement events, as appropriate.

Disorders of sleep and circadian rhythms

Sleep is fundamental to the survival of humans. However, knowledge regarding the role of sleep and its regulation is poorly understood. Genetics in flies, mice, and humans has led to a detailed understanding of some aspects of circadian regulation. Sleep homeostasis (the effect of increasing periods of wakefulness on our sleep propensity) is largely not understood. Sleep homeostasis is distinct from, but also linked to, the circadian clock. It is only in the last two decades that our understanding of some sleep disorders has been revealed. These breakthroughs were mostly fueled by intensive investigation using genetic tools. Although modern human genetics has revolutionized scientific research of neurologic disorders beginning ~35 years ago, studies of sleep and sleep disorders have lagged behind those of many neurologic diseases. This is due to the complexity in phenotyping behaviors like sleep and the fact that sleep is strongly influenced by environmental and other factors. We have long been aware that the amount of sleep required by individuals is normally distributed in the general population with small proportions of people being natural short or natural long sleepers. However, it has been less than a decade since Mendelian families of natural short sleepers have been recognized. Recent work has made significant advances and mechanistic insights of several sleep disorders as well as familial natural short sleepers by using ever-improving human genetic and cellular molecular tools. Given recent advances into genetic and biologic understanding of sleep, the hope of understanding this indispensable process is closer. Ultimately, our growing understanding will lead to more effective treatments of human sleep disorders.

An earlier time of scan is associated with greater threat-related amygdala reactivity

Time-dependent variability in mood and anxiety suggest that related neural phenotypes, such as threat-related amygdala reactivity, may also follow a diurnal pattern. Here, using data from 1,043 young adult volunteers, we found that threat-related amygdala reactivity was negatively coupled with time of day, an effect which was stronger in the left hemisphere (β = -0.1083, p-fdr = 0.0012). This effect was moderated by subjective sleep quality (β = -0.0715, p-fdr = 0.0387); participants who reported average and poor sleep quality had relatively increased left amygdala reactivity in the morning. Bootstrapped simulations suggest that similar cross-sectional samples with at least 300 participants would be able to detect associations between amygdala reactivity and time of scan. In control analyses, we found no associations between time and V1 activation. Our results provide initial evidence that threat-related amygdala reactivity may vary diurnally, and that this effect is potentiated among individuals with average to low sleep quality. More broadly, our results suggest that considering time of scan in study design or modeling time of scan in analyses, as well as collecting additional measures of circadian variation, may be useful for understanding threat-related neural phenotypes and their associations with behavior, such as fear conditioning, mood and anxiety symptoms, and related phenotypes.

Sleep disturbances in obsessive-compulsive disorder: Association with non-response to repetitive transcranial magnetic stimulation (rTMS)

Background Repetitive transcranial magnetic stimulation (rTMS) is a promising augmentation strategy for treatment-refractory OCD. However, a substantial group still fails to respond. Sleep disorders, e.g. circadian rhythm sleep disorders (CRSD), are highly prevalent in OCD and might mediate treatment response. The aims of the current study were to compare sleep disturbances between OCD patients and healthy subjects as well as between rTMS responders and non-responders, and most importantly to determine sleep-related predictors of rTMS non-response. Methods 22 OCD patients received at least 10 sessions rTMS combined with psychotherapy. Sleep disturbances were measured using questionnaires and actigraphy. Sleep in patients was compared to healthy subjects. Treatment response was defined as >35% reduction on YBOCS. Treatment response prediction models were based on measures of CRSD and insomnia. Results Sleep disturbances were more prevalent in OCD patients than healthy subjects. The OCD group consisted of 12 responders and 10 non-responders. The CRSD model could accurately predict non-response with 83% sensitivity and 63% specificity, whereas the insomnia model could not. Conclusions CRSD is more prevalent in OCD patients than healthy subjects, specifically in rTMS non-responders. Therefore, CRSD may serve as a biomarker for different subtypes of OCD corresponding with response to specific treatment approaches.

Abnormal environmental light exposure in the intensive care environment

PURPOSE

We sought to characterize ambient light exposure in the intensive care unit (ICU) environment to identify patterns of light exposure relevant to circadian regulation.

METHODS

A light monitor was affixed to subjects' bed at eye level in a modern intensive care unit and continuously recorded illuminescence for at least 24h per subject. Blood was sampled hourly and measured for plasma melatonin. Subjects underwent hourly vital sign and bedside neurologic assessments. Care protocols and the ICU environment were not modified for the study.

RESULTS

A total of 67,324 30-second epochs of light data were collected from 17 subjects. Light intensity peaked in the late morning, median 64.1 (interquartile range 19.7-138.7) lux. The 75th percentile of light intensity exceeded 100lx only between 9AM and noon, and never exceeded 150lx. There was no correlation between melatonin amplitude and daytime, nighttime or total light exposure (Spearman's correlation coefficients all <0.2 and p>0.5).

CONCLUSIONS

Patients' environmental light exposure in the intensive care unit is consistently low and follows a diurnal pattern. No effect of nighttime light exposure was observed on melatonin secretion. Inadequate daytime light exposure in the ICU may contribute to abnormal circadian rhythms.

Entrainment Maps

Circadian oscillators found across a variety of species are subject to periodic external light-dark forcing. Entrainment to light-dark cycles enables the circadian system to align biological functions with appropriate times of day or night. Phase response curves (PRCs) have been used for decades to gain valuable insights into entrainment; however, PRCs may not accurately describe entrainment to photoperiods with substantial amounts of both light and dark due to their reliance on a single limit cycle attractor. We have developed a new tool, called an entrainment map, that overcomes this limitation of PRCs and can assess whether, and at what phase, a circadian oscillator entrains to external forcing with any photoperiod. This is a 1-dimensional map that we construct for 3 different mathematical models of circadian clocks. Using the map, we are able to determine conditions for existence and stability of phase-locked solutions. In addition, we consider the dependence on various parameters such as the photoperiod and intensity of the external light as well as the mismatch in intrinsic oscillator frequency with the light-dark cycle. We show that the entrainment map yields more accurate predictions for phase locking than methods based on the PRC. The map is also ideally suited to calculate the amount of time required to achieve entrainment as a function of initial conditions and the bifurcations of stable and unstable periodic solutions that lead to loss of entrainment.

Comparative Review of Approved Melatonin Agonists for the Treatment of Circadian Rhythm Sleep-Wake Disorders

Circadian rhythm sleep‐wake disorders (CRSWDs) are characterized by persistent or recurrent patterns of sleep disturbance related primarily to alterations of the circadian rhythm system or the misalignment between the endogenous circadian rhythm and exogenous factors that affect the timing or duration of sleep. These disorders collectively represent a significant unmet medical need, with a total prevalence in the millions, a substantial negative impact on quality of life, and a lack of studied treatments for most of these disorders. Activation of the endogenous melatonin receptors appears to play an important role in setting the circadian clock in the suprachiasmatic nucleus of the hypothalamus. Therefore, melatonin agonists, which may be able to shift and/or stabilize the circadian phase, have been identified as potential therapeutic candidates for the treatment of CRSWDs. Currently, only one melatonin receptor agonist, tasimelteon, is approved for the treatment of a CRSWD: non–24‐hour sleep‐wake disorder (or non‐24). However, three additional commercially available melatonin receptor agonists—agomelatine, prolonged‐release melatonin, and ramelteon—have been investigated for potential use for treatment of CRSWDs. Data indicate that these melatonin receptor agonists have distinct pharmacologic profiles that may help clarify their clinical use in CRSWDs. We review the pharmacokinetic and pharmacodynamic properties of these melatonin agonists and summarize their efficacy profiles when used for the treatment of CRSWDs. Further studies are needed to determine the therapeutic potential of these melatonin agonists for most CRSWDs.

Diagnosis, Cause, and Treatment Approaches for Delayed Sleep-Wake Phase Disorder

Delayed sleep-wake phase disorder (DSWPD) is commonly defined as an inability to fall asleep and wake at societal times resulting in excessive daytime sleepiness. Although the cause is multifaceted, delays in sleep time are largely driven by misalignment between the circadian pacemaker and the desired sleep-wake timing schedule. Current treatment approaches focus on correcting the circadian delay; however, there is a lack of data investigating combined therapies for treatment of DSWPD.

[The current state of research in bright light therapy]

The significance of light for the human organism and especially for the mental health is well-established for a long time. Therefore, the impact of light on mood and the use of bright light as a treatment-option for affective disorders have been studied extensively by scientists. Today bright light therapy is the treatment of choice for saisonal affective disorders. In the last years several clinical trials could demonstrate the therapeutic efficacy of bright light therapy for different neurological and psychiatric disorders such as sleep disorders, non-seasonal affective disorders or dementia. This article will give an overview about the neurobiological basis for light therapy and discuss different disorders responsive to light therapy. Finally a short overview about technical aspects of light therapy and new developments in light engineering will be presented.

Synchrony and desynchrony in circadian clocks: impacts on learning and memory

Circadian clocks evolved under conditions of environmental variation, primarily alternating light dark cycles, to enable organisms to anticipate daily environmental events and coordinate metabolic, physiological, and behavioral activities. However, modern lifestyle and advances in technology have increased the percentage of individuals working in phases misaligned with natural circadian activity rhythms. Endogenous circadian oscillators modulate alertness, the acquisition of learning, memory formation, and the recall of memory with examples of circadian modulation of memory observed across phyla from invertebrates to humans. Cognitive performance and memory are significantly diminished when occurring out of phase with natural circadian rhythms. Disruptions in circadian regulation can lead to impairment in the formation of memories and manifestation of other cognitive deficits. This review explores the types of interactions through which the circadian clock modulates cognition, highlights recent progress in identifying mechanistic interactions between the circadian system and the processes involved in memory formation, and outlines methods used to remediate circadian perturbations and reinforce circadian adaptation.

Tasimelteon: first global approval

Tasimelteon (HETLIOZ™) is an orally bioavailable agonist of the melatonin MT1 and MT2 receptors that has been approved in the US for the treatment of non-24-hour sleep-wake disorder. It is the first US FDA-approved medication for this orphan indication. Melatonin is thought to play a role in governing the body's natural sleep-wake cycle through physiological processes regulated in the suprachiasmatic nucleus of the hypothalamus. The hormone is secreted by the pineal gland, with onset typically occurring when daylight begins to dim. In healthy, sighted individuals, the endogenous circadian period is a little over 24 hours, but is entrained to the 24-hour day through exposure to environmental cues, such as light and darkness. In the absence of these cues, synchronisation is lost and the circadian rhythm follows the intrinsic non-24-hour clock, resulting in disorders like non-24-hour sleep-wake disorder. Because the rhythm of endogenous melatonin is considered to be a measure of the human circadian phase, the carefully timed administration of melatonin analogues, such as tasimelteon, can potentially promote circadian readjustment. This article summarizes the milestones in the development of tasimelteon leading to this first approval for the treatment of non-24-hour sleep-wake disorder.