Circadian typology: a comprehensive review

Morningness-eveningness and social anxiety symptoms: the influence of depression symptoms on the indirect effect through punishment sensitivity and experiential avoidance

Social anxiety has recently been linked to morningness-eveningness; however, the psychological mechanisms underlying this relationship are not well known. As such, the purpose of the current study is to propose a model by which morningness-eveningness is related to social anxiety symptoms through punishment sensitivity and experiential avoidance within an adult American, community sample recruited via Amazon's Mechanical Turk (MTurk). It was hypothesized that experiential avoidance and punishment sensitivity would be associated with increased social anxiety symptoms and that morningness-eveningness would be negatively related to social anxiety symptoms. Furthermore, eveningness was hypothesized to be associated with increased punishment sensitivity and in turn, greater experiential avoidance. Lastly, the relationship between morningness-eveningness and social anxiety was hypothesized to be mediated by punishment sensitivity among the group with high depression levels, but not among the group with lesser depression symptoms. The results indicated that eveningness was related to social anxiety symptoms through experiential avoidance, and that depression symptoms influenced the relationship between morningness-eveningness and punishment sensitivity such that, in those high in depression symptoms, there was a significant association between eveningness and punishment sensitivity, but not among those with lower depression levels. The study findings build upon existing chronobiological research and addresses inconsistencies in previous literature.

Melatonin Administration Methods for Research in Mammals and Birds

Endocrine research in animals often entails exogenous hormone administration. Special issues arise when developing administration protocols for hormones with circadian and seasonal periodicity. This article reviews various methods for the exogenous administration of hormones with such periodicities by focusing on melatonin. We discuss that methodological variations across studies can affect experimental results. Melatonin administration techniques used in vertebrates includes infusion pumps, beeswax pellets, oral administration, injections, SILASTIC capsules, osmotic pumps, transdermal delivery, beads, and sponges.

Circadian rhythm in bipolar disorder: A review of the literature

Sleep disturbances and circadian rhythm dysfunction have been widely demonstrated in patients with bipolar disorder (BD). Irregularity of the sleep-wake rhythm, eveningness chronotype, abnormality of melatonin secretion, vulnerability of clock genes, and the irregularity of social time cues have also been well-documented in BD. Circadian rhythm dysfunction is prominent in BD compared with that in major depressive disorders, implying that circadian rhythm dysfunction is a trait marker of BD. In the clinical course of BD, the circadian rhythm dysfunctions may act as predictors for the first onset of BD and the relapse of mood episodes. Treatments focusing on sleep disturbances and circadian rhythm dysfunction in combination with pharmacological, psychosocial, and chronobiological treatments are believed to be useful for relapse prevention. Further studies are therefore warranted to clarify the relation between circadian rhythm dysfunction and the pathophysiology of BD to develop treatment strategies for achieving recovery in BD patients.

Overcoming insomnia: protocol for a large-scale randomised controlled trial of online cognitive behaviour therapy for insomnia compared with online patient education about sleep

INTRODUCTION

Insomnia is a major public health concern. While cognitive behaviour therapy for insomnia (CBT-I) is acknowledged as the best available intervention, there are unanswered questions about its wider dissemination, socioeconomic benefits and its impact on health resource utilisation. The aim of this randomised controlled trial (RCT) is to investigate the effectiveness of a fully automated online version of CBT-I compared with online patient education about sleep (PE). Outcome measures comprise changes in symptoms of insomnia, time off work due to sick leave as well as medication and health resource utilisation. Also, we will examine (i) putative mediators of the effects of CBT-I on insomnia severity and (ii) selected potential psycho-bio-social moderators of the effects of the interventions.

METHODS AND ANALYSIS

A parallel-group RCT will be conducted in a target sample of about 1500 adults recruited across Norway. Participants will complete an online screening and consent process. Those who meet eligibility criteria will be randomised to receive direct access to fully automated online CBT-I or to an online PE programme. The primary outcome is change in insomnia severity immediately postintervention; secondary outcomes are change in daytime functioning and other sleep measures postintervention and at 6-month and 24-month follow-up. Objective data from national registries will be obtained at two time points (1 year and 2 years post-treatment), allowing a mirror image study of preintervention and postintervention rates of sick leave, and of medication and healthcare utilisation by condition.

ETHICS AND DISSEMINATION

The study protocol was approved by the Regional Committee for Medical and Health Research Ethics in South East Norway (2015/134). Findings from the RCT will be disseminated in peer-reviewed publications and conference presentations. Exploratory analyses of potential mediators and moderators will be reported separately. User-friendly outputs will be disseminated to patient advocacy and other relevant organisations.

TRIAL REGISTRATION NUMBER

NCT02558647; Pre-results.

Absence of morningness alleles in non-European populations

In spite of suspected circadian differences between different ancestral groups, most human studies have used individuals of European descent. This also applies to three recent genome-wide association studies (GWAS), which pinpointed a number of chronotype loci. We investigated the distribution of these hits in different 1000 Genomes populations. We found 6 out of the 41 alleles previously identified by GWAS in European participants (in the genes RGS16, PER2 and AK5 and between the genes APH1A and CA14) to be absent from some non-European population groups. This highlights the need for ancestral diversity in circadian research and may reflect differences affecting the phenotype of individuals of East Asian ancestry.

The role of sleep in emotional memory processing in middle age

Sleep benefits memory in young adults, and this effect may be particularly strong for representations associated with negative emotion. Many aspects of sleep important for memory consolidation change with aging, particularly by middle age, suggesting that sleep-related consolidation may be reduced. However, the influence of sleep on memory has rarely been investigated in a middle-aged population. In the current study, young and middle-aged adults viewed negative and neutral pictures and underwent a recognition test after sleep or wake. Subjective emotional reactivity was also measured. Compared to waking, sleep benefited memory in young adults. Performance did not differ between sleep and wake groups in middle-aged adults, and it matched the level of young adults who slept. The effect of sleep versus wake was not influenced by memory valence in either age group. These results suggest the relative influence of sleep compared to wake on memory declines with aging, specifically by middle age, and that this decline extends to negative memory.

Effects of work arrangements on the sleep regimen of creative research and development employees

Traditional 'nine-to-five' working schedules do not consider individual characteristics. We identify what types of employees suffer from the adverse effects of work arrangements on their sleep regimen based on a survey of Estonian creative research and development (R&D) employees (N = 153). We present ordinary least squares and ordered probit regression estimates and recursive structural equation model estimates of the employees' perceived level of sleep regimen disruption. We find that evening-type employees, women and employees with a lower creative intensity of work perceive with a significantly higher probability that work limits their sleep, while employees having flexibility in both working time and workplace feel less impacted by work-driven constraints on their sleep regimen. Granting working time and workplace flexibility and avoiding the allocation of excessive administrative duties to creative R&D employees may have a considerable positive impact on improving their sleep, thus contributing to improving their well-being and work results.

Chronotype preferences of college students from varied altitude backgrounds in Ethiopia

The purpose of this study was to compare chronotype preferences of college students from high- and low-altitude backgrounds living in a tropical setting of Ethiopia. Chronotype (morningness-eveningness) is a preference for a given time of day for physical or mental activities. The present cross-sectional study employed Horne and Osteberg Morningness-Eveningness Questionnaires to evaluate chronotype preferences. The chronotype preference of 264 male college students from varied altitude backgrounds indicated significant differences (p < 0.001). Our findings confirm our hypothesis, of the prevalence of M-types dominant chronotype among college students at low than high altitude. However, we did not confirm our second hypothesis, since students from high-altitude backgrounds were generally I-type dominant chronotype. Similarly, students' academic performances from low- compared to high-altitudes backgrounds also indicated significant differences (p < 0.003). Better academic performances were seen in students with I-type chronotype orientations from high altitudes.

Circadian activity rhythm in adult attention-deficit hyperactivity disorder

The aim of the present study was to analyze the features of circadian motor activity rhythm of adult attention-deficit hyperactivity disorder (ADHD) patients, by means of functional linear modeling, within the theoretical framework of the two-process model of sleep regulation. Thirty-two ADHD patients and 32 healthy controls (HCs) participated the study. Actiwatch AW64 actigraph was used to quantify motor activity data in 1-min epochs. Participants wore the actigraph on the non-dominant wrist for seven consecutive days. Results show that ADHD patients had significantly higher motor activity than HCs from 4:00 to 7:00, with a peak around 5:00, and from 12:00 to 18:00, with another peak around 14:00. According to the two-process model of sleep regulation, the circadian activity rhythm of ADHD patients may indicate a lower homeostatic sleep pressure, as reflected by the absence of post-lunch dip, which could be considered a potential trait marker of adult ADHD.

Heterogeneity of sleep quality in relation to circadian preferences and depressive symptomatology among major depressive patients

BACKGROUND

The current study aimed at investigating the latent dimensional structure of sleep quality as indexed by the seven components of the Pittsburgh Sleep Quality Index (PSQI), as well as latent covariance structure between sleep quality, circadian preferences and depressive symptoms.

METHODS

Two hundred twenty-five patients with major depressive disorder (MDD), with an average age of 29.92 ± 10.49 years (aged between 17 and 63), participated in the study. The PSQI, Morningness-Eveningness Questionnaire (MEQ) and Beck Depression Inventory (BDI) were administered to participants. Four sets of latent class analyses were subsequently run to obtain optimal number of latent classes best fit to the data.

RESULTS

Mixture models revealed that sleep quality is multifaceted in MDD. The data best fit to four-latent-class model: Poor Habitual Sleep Quality (PHSQ), Poor Subjective Sleep Quality (PSSQ), Intermediate Sleep Quality (ISQ), and Good Sleep Quality (GSQ). MDD patients classified into GSQ latent class (23.6%) reported the lowest depressive symptoms and were more prone to morningness diurnal preferences compared to other three homogenous sub-groups. Finally, the significant association between eveningness diurnal preferences and depressive symptomatology was significantly mediated by poor sleep quality.

LIMITATION

The cross-sectional nature of the study and the lack of an objective measurement of sleep such as polysomnography recordings was the most striking limitation of the study.

CONCLUSIONS

We concluded sleep quality in relation to circadian preferences and depressive symptoms has a heterogeneous nature in MDD.

Rhythmicity of Mood Symptoms in Individuals at Risk for Psychiatric Disorders

Despite emerging evidence that disruption in circadian rhythms may contribute to the pathophysiology of psychiatric disorders, there is a significant knowledge gap on the rhythmicity of psychological symptoms. Here, we aimed at investigating the rhythmicity of mood symptoms in individuals at risk for psychiatric disorders. 391 Brazilian and 317 Spanish participants completed the Self-Reporting Questionnaire-20 for non-psychotic mental disorders; the Mood Rhythm Instrument was used to assess rhythmicity of mood symptoms and the Munich ChronoType Questionnaire to assess sleep patterns. We found that the rhythmicity of specific mood-related symptoms and behaviors, particularly pessimism and motivation to exercise, were associated with being at risk for psychiatric disorders, even after controlling for sleep timing, sleep deficit, and season of data collection. We also found that the peak of some mood symptoms and behaviors were different between individuals at high vs. low risk for psychiatric disorders, with specific differences between countries. These results are consistent with previous research showing that circadian misalignment is associated with higher risk for mental health conditions. These findings also suggest that lifestyle changes preventing circadian misalignment might be useful to reduce the risk of psychiatric disorders, where cultural differences must be taken into account.

Young adults are more vulnerable to chronic sleep deficiency and recurrent circadian disruption than older adults

More than a third of US adults report fewer than 6 hours of sleep a night, making chronic sleep restriction a growing public health concern. Sleep curtailment is associated with an increase in industrial accidents, motor vehicle accidents, medical and other occupational errors. Young adults are more vulnerable to acute sleep deprivation than older adults, but less is known about how young vs. older adults respond to the more commonly experienced chronic sleep restriction. To test the hypothesis that young adults are more vulnerable to chronic sleep loss than older adults, we compared data from young and older adults who underwent three weeks of chronic sleep restriction (equivalent to 5.6 hours/24 hours) combined with recurrent circadian disruption in an experiment that enabled us to separate the influences of the sleep-wake homeostatic process, the circadian timing system, and the chronic sleep deficit. We found that while young and older adults reported similar levels of subjective sleepiness, objective measures of sleepiness revealed that young adults were more vulnerable and had more attentional failures than the older adults. These results have important public health implications, particularly related to prevention of sleep-related motor vehicle crashes in young drivers. Further research is needed to understand the neurobiological basis of these age-related differences.

Teenage night owls or early birds? Chronotype and the mental health of adolescents

Evidence suggests that the timing of sleep (chronotype) impacts mental health in young people, but previous studies have not accounted for sleep duration or school start time in this association, or examined a broad range of mental outcomes. In this study, we investigated the association between chronotype and mental health in a representative sample of adolescents from the 2014 Canadian Health Behaviour in School-Aged Children survey (29,635 students, 362 schools). We examined positive and negative aspects of mental health, using scores for emotional problems (range 0-33), emotional well-being (0-22), behavioural problems (0-28) and prosocial behaviours (0-25). We estimated chronotype using the time of mid-sleep on weekends and examined the associations using multilevel regressions, adjusted for sleep duration, school start time, individual, family and geographic characteristics. The average time of mid-sleep (chronotype) was 04:11 hr. An hour delay in mid-sleep time was associated with more emotional problems (0.34 [95% confidence interval 0.23, 0.45] point higher score), more behavioural problems (2.0% [95% confidence interval 1.4%, 2.6%] higher score), less emotional well-being (0.19 [95% confidence interval 0.09, 0.20] point lower score), and fewer prosocial behaviours (0.18 [95% confidence interval 0.08, 0.29] point lower score). A later chronotype was associated with poorer mental health, independent of sleep duration and school start time, and across internalizing and externalizing mental health domains. Further research is needed to clarify the mechanisms underlying this association. The timing of sleep, and not just its duration, may be an additional consideration for youth mental health.

Relevance of a Mobile Internet Platform for Capturing Inter- and Intrasubject Variabilities in Circadian Coordination During Daily Routine: Pilot Study

Background

Experimental and epidemiologic studies have shown that circadian clocks’ disruption can play an important role in the development of cancer and metabolic diseases. The cellular clocks outside the brain are effectively coordinated by the body temperature rhythm. We hypothesized that concurrent measurements of body temperature and rest-activity rhythms would assess circadian clocks coordination in individual patients, thus enabling the integration of biological rhythms into precision medicine.

Objective

The objective was to evaluate the circadian clocks’ coordination in healthy subjects and patients through simultaneous measurements of rest-activity and body temperature rhythms.

Methods

Noninvasive real-time measurements of rest-activity and chest temperature rhythms were recorded during the subject’s daily life, using a dedicated new mobile electronic health platform (PiCADo). It involved a chest sensor that jointly measured accelerations, 3D orientation, and skin surface temperature every 1-5 min and relayed them out to a mobile gateway via Bluetooth Low Energy. The gateway tele-transmitted all stored data to a server via General Packet Radio Service every 24 hours. The technical capabilities of PiCADo were validated in 55 healthy subjects and 12 cancer patients, whose rhythms were e-monitored during their daily routine for 3-30 days. Spectral analyses enabled to compute rhythm parameters values, with their 90% confidence limits, and their dynamics in each subject.

Results

All the individuals displayed a dominant circadian rhythm in activity with maxima occurring from 12:09 to 20:25. This was not the case for the dominant temperature period, which clustered around 24 hours for 51 out of 67 subjects (76%), and around 12 hours for 13 others (19%). Statistically significant sex- and age-related differences in circadian coordination were identified in the noncancerous subjects, based upon the range of variations in temperature rhythm amplitudes, maxima (acrophases), and phase relations with rest-activity. The circadian acrophase of chest temperature was located at night for the majority of people, but it occurred at daytime for 26% (14/55) of the noncancerous people and 33% (4/12) of the cancer patients, thus supporting important intersubject differences in circadian coordination. Sex, age, and cancer significantly impacted the circadian coordination of both rhythms, based on their phase relationships.

Conclusions

Complementing rest-activity with chest temperature circadian e-monitoring revealed striking intersubject differences regarding human circadian clocks’ coordination and timing during daily routine. To further delineate the clinical importance of such finding, the PiCADo platform is currently applied for both the assessment of health effects resulting from atypical work schedules and the identification of the key determinants of circadian disruption in cancer patients.

Associations between psychometrically assessed life history strategy and daily behavior: data from the Electronically Activated Recorder (EAR)

Life history theory has generated cogent, well-supported hypotheses about individual differences in human biodemographic traits (e.g., age at sexual maturity) and psychometric traits (e.g., conscientiousness), but little is known about how variation in life history strategy (LHS) is manifest in quotidian human behavior. Here I test predicted associations between the self-report Arizona Life History Battery and frequencies of 12 behaviors observed over 72 h in 91 US college students using the Electronically Activated Recorder (EAR), a method of gathering periodic brief audio recordings as participants go about their daily lives. Bayesian multi-level aggregated binomial regression analysis found no strong associations between ALHB scores and behavior frequencies. One behavior, presence at amusement venues (bars, concerts, sports events) was weakly positively associated with ALHB-assessed slow LHS, contrary to prediction. These results may represent a challenge to the ALHB's validity. However, it remains possible that situational influences on behavior, which were not measured in the present study, moderate the relationships between psychometrically-assessed LHS and quotidian behavior.

Schizotypy and Performance on an Insight Problem-Solving Task: The Contribution of Persecutory Ideation

Insight problem solving is thought to underpin creative thought as it incorporates both divergent (generating multiple ideas and solutions) and convergent (arriving at the optimal solution) thinking approaches. The current literature on schizotypy and creativity is mixed and requires clarification. An alternate approach was employed by designing an exploratory web-based study using only correlates of schizotypal traits (paranoia, dissociation, cognitive failures, fantasy proneness, and unusual sleep experiences) and examining which (if any) predicted optimal performance on an insight problem-solving task. One hundred and twenty-one participants were recruited online from the general population and completed the number reduction task. The discovery of the hidden rule (HR) was used as a measure of insight. Multivariate logistic regression analyses highlighted persecutory ideation to best predict the discovery of the HR (OR = 1.05; 95% CI 1.01–1.10, p = 0.017), with a one-point increase in persecutory ideas corresponding to the participant being 5% more likely to discover the HR. This result suggests that persecutory ideation, above other schizotypy correlates, may be involved in insight problem solving.

Eveningness and its possibility of predicting burnout symptoms among physicians and nurses – preliminary results

Introduction.

A sense of burnout may seriously impair one’s functioning and well-being. It may also hamper the quality of care over a patient. The present study therefore assesses sleep quality and chronotype as predictors of a sense of burnout in physicians and nurses of a district hospital.

Material and methods.

The study group comprised 16 physicians and 31 nurses of a district hospital in Central Poland. The participants completed the Link Burnout Questionnaire (LBQ), Chronotype Questionnaire, and Pittsburgh Sleep Quality Inventory. A linear regression model was constructed for each LBQ dimension by means of stepwise elimination. Each model was adjusted to empirical data (p<0.05).

Results.

A rise in Psychophysical exhaustion was predicted by greater scores for Morningness-Eveningness (ME) and Distinctness (DI) of the rhythm. A higher ME score was associated with higher scores in Relationship deterioration and Sense of professional ineffectiveness, with the latter also associated with presence in the nurses group. The nurses group also demonstrated higher Disillusionment and Psychophysical exhaustion scores than the physicians group.

Conclusions.

Eveningness predicted greater burnout in the studied sample. Thus, chronotype should be considered an important burnout risk factor and it can act as a starting point for devising behavioural interventions.

Fitness consequences of fish circadian behavioural variation in exploited marine environments

The selective properties of fishing that influence behavioural traits have recently gained interest. Recent acoustic tracking experiments have revealed between-individual differences in the circadian behavioural traits of marine free-living fish; these differences are consistent across time and ecological contexts and generate different chronotypes. Here, we hypothesised that the directional selection resulting from fishing influences the wild circadian behavioural variation and affects differently to individuals in the same population differing in certain traits such as awakening time or rest onset time. We developed a spatially explicit social-ecological individual-based model (IBM) to test this hypothesis. The parametrisation of our IBM was fully based on empirical data; which represent a fishery formed by patchily distributed diurnal resident fish that are exploited by a fleet of mobile boats (mostly bottom fisheries). We ran our IBM with and without the observed circadian behavioural variation and estimated selection gradients as a quantitative measure of trait change. Our simulations revealed significant and strong selection gradients against early-riser chronotypes when compared with other behavioural and life-history traits. Significant selection gradients were consistent across a wide range of fishing effort scenarios. Our theoretical findings enhance our understanding of the selective properties of fishing by bridging the gaps among three traditionally separated fields: fisheries science, behavioural ecology and chronobiology. We derive some general predictions from our theoretical findings and outline a list of empirical research needs that are required to further understand the causes and consequences of circadian behavioural variation in marine fish.

Blue-Enriched Light Enhances Alertness but Impairs Accurate Performance in Evening Chronotypes Driving in the Morning

Attention maintenance is highly demanding and typically leads to vigilance decrement along time on task. Therefore, performance in tasks involving vigilance maintenance for long periods, such as driving, tends to deteriorate over time. Cognitive performance has been demonstrated to fluctuate over 24 h of the day (known as circadian oscillations), thus showing peaks and troughs depending on the time of day (leading to optimal and suboptimal times of day, respectively). Consequently, vigilance decrements are more pronounced along time on task when it is performed at suboptimal times of day. According to research, light exposure (especially blue-enriched white) enhances alertness. Thus, it has been proposed to prevent the vigilance decrement under such adverse circumstances. We aimed to explore the effects of blue-enriched white light (vs. dim light) on the performance of a simulated driving task at a suboptimal time of day. A group of evening-types was tested at 8 am, as this chronotype had previously shown their largest vigilance decrement at that time. In the dim light condition, vigilance decrements were expected on both subjective (as increments in the Karolinska Sleepiness Scale scores) and behavioral measures [as slower reaction times (RTs) in the auditory Psychomotor Vigilance Task, slower RTs to unexpected events during driving, and deteriorated driving accuracy along time on task]. Physiological activation was expected to decrease (as indexed by an increase of the distal-proximal temperature gradient, DPG). Under blue-enriched white light, all these trends should be attenuated. Results from the control dim light condition replicated the vigilance decrement in all measures. Most important, the blue-enriched white light attenuated this decrement, leading to both lower DPG and faster RTs. However, it impaired accuracy of driving performance, and did not have any effect on subjective sleepiness. We conclude that exposure to blue-enriched light provides an effective countermeasure to enhance vigilance performance at suboptimal times of day, according to measures such as RTs. However, it should be considered that alerting effects of light could impair accuracy in precision tasks as keeping a proper car position. The current findings provide ergonomic implications for safety and fatigue related management systems.

The concept of chronotypes and its clinical importance for depressive disorders

Chronobiology and chronobiological research deal with time-dependent physiological processes and behavioral correlates as well as their adaptation to environmental conditions. Chronobiological research is presently focused on the impact of circadian rhythms on human behavior. In the last three decades, chronobiology has established itself as an independent area of research evolving to an important field of clinical psychology and psychiatry. In this overview, the results of studies on the clinical importance of chronotypes are summarized. The main focus is on the role of chronotype in depressive disorders.

Redox Mechanisms in Migraine: Novel Therapeutics and Dietary Interventions

SIGNIFICANCE

Migraine represents the third most prevalent and the seventh most disabling human disorder. Approximately 30% of migraine patients experience transient, fully reversible, focal neurological symptoms (aura) preceding the attack. Recent Advances: Awareness of the hypothesis that migraine actually embodies a spectrum of illnesses-ranging from episodic to chronic forms-is progressively increasing and poses novel challenges for clarifying the underlying pathophysiological mechanisms of migraine as well as for the development of novel therapeutic interventions. Several theories have evolved to the current concept that a combination of genetic, epigenetic, and environmental factors may play a role in migraine pathogenesis, although their relative importance is still being debated.

CRITICAL ISSUES

One critical issue that deserves a particular attention is the role of oxidative stress in migraine. Indeed, potentially harmful oxidative events occur during the migraine attack and long-lasting or frequent migraine episodes may increase brain exposure to oxidative events that can lead to chronic transformation. Moreover, a wide variety of dietary, environmental, physiological, behavioral, and pharmacological migraine triggers may act through oxidative stress, with clear implications for migraine treatment and prophylaxis. Interestingly, almost all current prophylactic migraine agents exert antioxidant effects.

FUTURE DIRECTIONS

Increasing awareness of the role of oxidative stress and/or decreased antioxidant defenses in migraine pathogenesis and progression to a chronic condition lays the foundations for the design of novel prophylactic approaches, which, by reducing brain oxidative phenomena, could favorably modify the clinical course of migraine. Antioxid. Redox Signal. 28, 1144-1183.

Effect of bright light therapy on delayed sleep/wake cycle and reaction time of athletes participating in the Rio 2016 Olympic Games

This study investigated the effect of using an artificial bright light on the entrainment of the sleep/wake cycle as well as the reaction times of athletes before the Rio 2016 Olympic Games. A total of 22 athletes from the Brazilian Olympic Swimming Team were evaluated, with the aim of preparing them to compete at a time when they would normally be about to go to bed for the night. During the 8-day acclimatization period, their sleep/wake cycles were assessed by actigraphy, with all the athletes being treated with artificial light therapy for between 30 and 45 min (starting at day 3). In addition, other recommendations to improve sleep hygiene were made to the athletes. In order to assess reaction times, the Psychomotor Vigilance Test was performed before (day 1) and after (day 8) the bright light therapy. As a result of the intervention, the athletes slept later on the third (p = 0.01), seventh (p = 0.01) and eighth (p = 0.01) days after starting bright light therapy. Regarding reaction times, when tested in the morning the athletes showed improved average (p = 0.01) and minimum reaction time (p = 0.03) when comparing day 8 to day 1. When tested in the evening, they showed improved average (p = 0.04), minimum (p = 0.03) and maximum reaction time (p = 0.02) when comparing day 8 to day 1. Light therapy treatment delayed the sleep/wake cycles and improved reaction times of members of the swimming team. The use of bright light therapy was shown to be effective in modulating the sleep/wake cycles of athletes who had to perform in competitions that took place late at night.

Eveningness chronotype, insomnia symptoms, and emotional and behavioural problems in adolescents

OBJECTIVE

Eveningness tendency and insomnia are common in adolescents, but whether they have an independent or synergistic effect on the risk of psychopathology have remained undefined. The present study aimed to examine eveningness chronotype and insomnia symptoms in relation to mental health and emotional and behavioural problems in a community-based adolescent population.

METHODS

A total of 4948 adolescents (weighted mean age: 14.5 ± 1.8 years, weighted percentage of females: 48.9%) completed the measures. Insomnia was assessed by the Insomnia Severity Index (ISI), and chronotype preference was measured by the reduced version of the Morningness-Eveningness Questionnaire (MEQ). Emotional and behavioural problems and mental health were assessed by the Strengths and Difficulties Questionnaire (SDQ) and the General Health Questionnaire (GHQ-12), respectively. Potential confounders including demographic factors, pubertal status, general health, and sleep duration were controlled for in the analyses.

RESULTS

Insomnia symptoms were prevalent in evening-type adolescents (52% vs intermediate-type: 34.3%, morning-type: 18.0%, p < 0.001), especially two subtypes of insomnia symptoms, including difficulty initiating sleep and difficulty maintaining sleep. Eveningness and insomnia were independently associated with an increased risk of having emotional and behavioural problems (eveningness: adjusted odds ratio [AdjOR] = 1.88, 95% confidence interval [CI] = 1.61-2.19, p < 0.001; insomnia: AdjOR = 3.66, 95% CI = 2.73-4.91) as well as poor mental health in adolescents (eveningness: AdjOR = 1.25, 95% CI = 1.04-1.52, p < 0.001; insomnia: AdjOR = 3.63, 95% CI = 2.41-5.03).

CONCLUSIONS

Eveningness and insomnia symptoms are independently associated with the risk of psychopathology in adolescents. Our findings underscore the need to address both sleep and circadian factors in assessing and managing emotional and behavioural problems in the adolescent population.

Chronotype and Psychiatric Disorders

PURPOSE OF REVIEW

Chronotype, reflecting interindividual differences in daily activity patterns and sleep-wake cycles, is intrinsically connected with well-being. Research indicates increased risk of many adverse mental health outcomes for evening-type individuals. Here, we provide an overview of the current evidence available on the relationship between chronotype and psychiatric disorders.

RECENT FINDINGS

The association between eveningness and depression is well established cross-sectionally, with preliminary support from longitudinal studies. The mechanisms underlying this relationship warrant further research; deficient cognitive-emotional processes have recently been implicated. Eveningness is associated with unhealthy lifestyle habits, and the propensity of evening types to addiction has been recognized. Chronotype may also be implicated in disordered eating.

SUMMARY

Eveningness is associated with depression-including seasonal affective disorder (SAD)-and substance dependence, while support for a relation with anxiety disorders and psychosis is lacking. In bipolar disorder, chronotype is linked to depression but not mania. Eveningness is also related to sleep disturbances and poor lifestyle habits, which may increase risk for psychiatric disorders.

Chronotype and response to training during the polar night: a pilot study

BACKGROUND

An individual's chronotype influences his or her physiological rhythms. Some studies have looked at the effect of time of day on the responses to exercise, but studies on the effect of long-term training are lacking.

OBJECTIVE

To report the effects of an 8-week training period during the polar night in non-athletes of different chronotypes living at 70°N.

DESIGN

In all, 10 morning (M), 10 neither (N) and 10 evening (E) types were recruited, and their aerobic capacity (VO_2max), strength, flexibility and balance before and after the training period were tested.

RESULTS

3 E-types, 5 N-types and 6 M-types completed the protocol. An increase in VO_2max and strength was observed for the whole group. The best negative correlation (r=-0.5287) was found between the Morningness-Eveningness Questionnaire (MEQ) score and the increase in VO2max, and the best positive correlation (r=0.4395) was found between MEQ and the increase in strength. Changes in balance and flexibility did not show any clear trends.

CONCLUSION

In an environment with no outdoor daylight, it seems that the response to 8 weeks of aerobic training is larger in the E- than in the M-types, although the M-types showed a larger improvement in strength.

Work routines moderate the association between eveningness and poor psychological well-being

Well-being is a useful screening method for the detection of mood disorders. Evidence associating psychological well-being with sleep-wake patterns exists, as well as associations with sleep-wake patterns, work-related parameters, and perceived self-efficacy. Despite the growing research regarding the relationship between these factors and mental health, there are few studies that analyze them together. OBJECTIVE: To investigate if the association between sleep-wake patterns and psychological well-being is mediated or moderated by perceived self-efficacy, work flexibility and work routines. MATERIAL AND METHODS: This cohort study was performed in southern Brazil. A sample of 987 individuals was analyzed (66.9% women; mean age = 43.9 years). Work routines parameters and work schedule flexibility were evaluated, most participants were farmers (46%) and most worked 7 days a week (69.1%). Munich Chronotype Questionnaire (MCTQ) was administered for evaluation of sleep-wake patterns, General Self-Efficacy Scale (GSE) for assessment the participants’ beliefs about how they coped with daily hassles, and World Health Organization Five-item Well-being Index (WHO-5) for evaluation of psychological well-being levels. Moderation and mediation models were tested. RESULTS: The moderation model showed influences of work end time on the relationship between sleep onset time and psychological well-being (R² = 0.147; F = 24.16; p<0.001). The final regression model showed an association of psychological well-being with sex (Beta = -0.086; p = 0.004), sleep onset time (Beta = -0.086; p = 0.006), and self-efficacy (Beta = 0.316; p<0.001); the work end time showed association in the interaction with sleep onset time (Beta = -0.075; p = 0.016). CONCLUSION: The findings support the direct association of psychological well-being with sleep-wake patterns and self-efficacy, and show an interaction between work routines and sleep-wake patterns. Our results draw attention to the importance of the interplay between individual and social rhythms in relation to psychological well-being.

Similarity in Chronotype and Preferred Time for Sex and Its Role in Relationship Quality and Sexual Satisfaction

Recently, the issue of diurnal preferences has been increasingly studied within the context of romantic relationships and sexual functioning. In the present paper we apply a dyadic design to investigate the role of romantic partners' diurnal preferences in determining a variety of relationship outcomes. A sample of 91 heterosexual couples completed a set of questionnaires measuring relationship satisfaction, sexual satisfaction, and morningness-eveningness, and answered questions regarding their actual and preferred time for sexual activity. Conducted analyses revealed that similarity in chronotype between partners and female morningness fostered relationship satisfaction in females, but not in males. Furthermore, morningness-eveningness was associated with preferred time for sex in males, but not in females, who in principle preferred evening hours. Although actual time for sex was up to the female preference, sexual satisfaction in both genders was associated with lower discrepancy in their preferred time for sex and greater frequency of intercourse. In sum, these results indicate that chronotype and time for sex are important factors affecting sexual and relationships satisfaction in heterosexual couples.

Use of social media is associated with short sleep duration in a dose-response manner in students aged 11 to 20 years

AIM

This study examined the association between social media and sleep duration among Canadian students aged 11-20.

METHODS

Data from 5242 students were obtained from the 2015 Ontario Student Drug Use and Health Survey, a province-wide, school-based survey that has been conducted every two years since 1977. We measured the respondents' sleep duration against the recommended ranges of 9-11 h per night at 11-13 years of age, 8-10 h at 14-17 and 7-9 h per night for those aged 18 years or more.

RESULTS

Overall, 36.4% of students met or exceeded the recommended sleep duration and 63.6% slept less than recommended, with 73.4% of students reporting that they used social media for at least one hour per day. After adjusting for various covariates, the use of social media was associated with greater odds of short sleep duration in a dose-response manner (p for linear trend <0.001). Odds ratios ranged from 1.82 for social media use of at least one hour per day to 2.98 for at least five hours per day.

CONCLUSION

Greater use of social media was associated with shorter sleep duration in a dose-response fashion among Canadian students aged 11-20.

Associations of depression and seasonality with morning-evening preference: Comparison of contributions of its morning and evening components

Despite predominance of positive findings on associations of morning-evening preference with seasonality and depression, it remains to be clarified whether morning and evening components of this preference equally contribute to these associations and whether these associations persist after accounting for confounding variables. Data on retrospectively reported seasonal changes in well-being, mood, and behaviors were collected from 2398 residents of West Siberia, South and North Yakutia, Chukotka, Alaska, and Turkmenistan. Other self-reports included mental and physical health, sleep duration, and adaptabilities of the sleep-wake cycle. Depression was found to be linked to morning rather than evening component of morning-evening preference, i.e., morning lateness. Morning lateness was also linked to retrospectively reported degree of seasonal changes rather than to severity of problems associated with such changes. Variation in morning-evening preference explained not more than 2% and 4% of the total variation in depression and seasonality, respectively. The associations became even weaker but remained significant after accounting for other differences between respondents, such as their gender, age, physical health, and adaptability of their sleep-wake cycle. These results have practical relevance for understanding of the roles playing by morning earliness and insensitivity to seasonal changes in the environment to protection against different mood disorders.

Morningness-Eveningness questionnaire in bipolar disorder

The Morningness-Eveningness Questionnaire (MEQ) is among the most commonly used scales to measure chronotype. We aimed to evaluate psychometric properties and clinical correlates of MEQ in bipolar disorder. Patients with a clinical diagnosis of bipolar disorder (n = 53) answered questionnaires for chronotype (MEQ), mood (Quick Inventory of Depressive Symptoms-16, Altman Self-Rating Mania Scale), insomnia (Athens Insomnia Scale, AIS), and sleepiness (Epworth Sleepiness Scale). Mood was evaluated using Montgomery-Åsberg Depression Rating Scale and Young Mania Rating Scale. The MEQ showed high internal consistency with Cronbach's alpha of .85. Lower MEQ scores (eveningness) correlated with insomnia (AIS) (r = -.34, p = .013). The estimate for eveningness (13/53, 24.5%) in our study was higher than in comparable studies in the general population. Patients on lithium exhibited a higher mean MEQ score (56.0 on lithium vs 46.9 with no lithium, p = .007), whereas this score was lower for patients on an antidepressant (46.0 on antidepressants vs 52.6 with no antidepressants, p = .023). We conclude that the MEQ score is psychometrically reliable. However, future studies should further evaluate the association of medication with chronotype. Validation of categorical cut-offs for MEQ in a larger sample of bipolar patients is needed to increase clinical utility.

Daily variation of visual sensitivity to luminance contrast: Effects of time of measurement and circadian typology

This study analyzed the fluctuation of the achromatic visual contrast sensitivity (CS) of adult males (M = 23.42 ± 2.6 years) during a daily period. Twenty-eight volunteers were divided into three groups according to circadian typology (CT): moderate morning (MM; n = 8); intermediate (I; n = 10) and moderate evening (ME; n = 10). The Pittsburgh Sleep Quality Index was used to evaluate sleep quality, and the Horne and Ostberg Morningness-Eveningness Questionnaire was used to measure CT. To measure CS, we used Metropsis software version 11.0 with vertical sinusoidal grids of 0.2, 0.6, 1, 3.1, 6.1, 8.8, 13.2 and 15.6 cycles per degree of visual angle (cpd). The stimuli were presented on a cathode ray tube (CRT) color video monitor with a 19-inch flat screen, a 1024 × 786 pixel resolution, a 100 Hz refresh rate and a photopic luminance of 39.6 cd/m². It was inferred that there is a tendency for visual contrast to vary according to daily rhythmicity and CT, mainly for the median spatial frequencies (1.0 cpd, χ² = 9.93, p < 0.05 and 3.1 cpd, χ² = 10.33, p < 0.05) and high spatial frequencies (13.2 cpd, χ² = 11.54, p < 0.05) of ME participants. ME participants had minimal visual contrast sensitivity during the morning shift and a progressive increase from afternoon to night.