Circadian typology: a comprehensive review

Circadian Rhythmic Characteristics in Men With Substance Use Disorder Under Treatment. Influence of Age of Onset of Substance Use and Duration of Abstinence

There is evidence of the reciprocal influence between the alteration of circadian rhythms and Substance Use Disorders (SUD), and part of the success of the SUD treatment lays in the patient's rhythmic recovery. We aim to elucidate the effect of the SUD treatment in circadian rhythmicity considering, for the first time, the age of onset of substance use (OSU) and duration of abstinence. We registered the sleep-wake schedules, the chronotype and the distal skin temperature of 114 SUD patients with at least 3 months of abstinence, considering whether they had begun consumption at age 16 or earlier (OSU ≤ 16, n = 56) or at 17 or later (OSU ≥ 17, n = 58), and duration of abstinence as short (SA: 3 to 5 months, n = 38), medium (MA: 6 to 9 months, n = 35) or long (LA: more than 9 months, n = 41). Moreover, we compared the patients' distal skin temperature pattern with a similar sample of healthy controls (HC, n = 103). SUD patients showed a morningness tendency and higher night values, amplitude and stability, a better adjustment to the cosine model and lower minimum temperature and circadianity index in the distal skin temperature rhythm, in contrast to the HC group. The OSU ≥ 17 and LA groups showed a more robust distal skin temperature pattern, as well as milder clinical characteristics when compared to the OSU ≤ 16 and SA groups, respectively. The circadian disturbances associated to substance consumption seem to improve with treatment, although the age of OSU and the duration of abstinence are modulating variables. Our results highlight the need to include chronobiological strategies that boost circadian rhythmicity both in SUD prevention and rehabilitation programs. The measurement of distal skin temperature rhythm, a simple and reliable procedure, could be considered an indicator of response to treatment in SUD patients.

Role of Chronobiology as a Transdisciplinary Field of Research: Its Applications in Treating Mood Disorders

Chronobiology is a field that studies the effects of time on biological systems. Periodicity is of particular interest. The master biological clock in the suprachiasmatic nucleus controls daily rhythms of core body temperature, rest-activity cycle, physiological and behavioral functions, psychomotor functions and mood in humans. The clock genes are involved in the generation of the circadian rhythms and the biological clock is synchronized to solar day by direct photic inputs. Various circadian rhythm abnormalities have been demonstrated in mood disorders such as unipolar depression, bipolar depression and seasonal affective disorder. Hypotheses involving circadian rhythm abnormalities related to the etiology of mood disorders have been raised. The resulting circadian rhythm changes can be measured and evaluated that these techniques can be used to identify subtypes of mood disorders associated with circadian rhythm changes. The data obtained from chronobiological studies reveal methods that manipulate circadian rhythms. The effects of light and melatonin on circadian rhythms are determined by these studies. Chronobiological research has been applied to the psychiatric clinic and light therapy has been used as a chronotherapeutic in the treatment of mood disorders. On the other hand, chronotherapeutic approaches with effects on circadian rhythms such as sleep deprivation therapy have been used in the treatment of mood disorders too. As a good example of translational psychiatry, chronobiological studies have been projected in the psychiatry clinic. It may be possible, the data obtained from the basic sciences are used in the diagnosis of mood disorders and in the treatment of psychiatric disorders as chronotherapeutic techniques. Developments in the field of chronobiology and data obtained from chronotherapeutics may enable the development of evidence-based diagnosis and treatment in psychiatry.

Melatonin as a treatment for mood disorders: a systematic review

OBJECTIVE

Melatonin has been widely studied in the treatment of sleep disorders and evidence is accumulating on a possible role for melatonin influencing mood. Our aim was to determine the efficacy and acceptability of melatonin for mood disorders.

METHOD

We conducted a comprehensive systematic review of randomized clinical trials on patients with mood disorders, comparing melatonin to placebo.

RESULTS

Eight clinical trials were included; one study in bipolar, three in unipolar depression and four in seasonal affective disorder. We have only a small study on patients with bipolar disorder, while we have more studies testing melatonin as an augmentation strategy for depressive episodes in major depressive disorder and seasonal affective disorder. The acceptability and tolerability were good. We analyzed data from three trials on depressive episodes and found that the evidence for an effect of melatonin in improving mood symptoms is not significant (SMD = 0.37; 95% CI [-0.05, 0.37]; P = 0.09). The small sample size and the differences in methodology of the trials suggest that our results are based on data deriving from investigations occurring early in this field of study.

CONCLUSION

There is no evidence for an effect of melatonin on mood disorders, but the results are not conclusive and justify further research.

Influence of time-of-day on joint Navon effect

The shared attention theory suggests that people devote greater cognitive resources to those features co-attended simultaneously with others, determining better performance in several types of tasks. When co-actors performed a go/no-go Navon task attending different features of target letters, the performance was impaired, reflecting a joint Navon effect (the representation of a co-actor's attentional focus made it more difficult to select and apply one's own focus of attention), probably due to asynchronous co-attention with a decrease in cognitive resources involved. Researches in chronobiology and chronopsychology demonstrated that not only selective attention (involved in a Navon task), but also cognitive resources have a daily fluctuations, mainly paralleling the circadian rhythm of body temperature (i.e. increasing values from the morning to evening with a subsequent decline in the night). The study was conducted to assess whether the presence of joint attention, as measured by the joint Navon effect, was influenced by the time-of-day. Sixteen pairs of participants sitting next to each other were required to respond to the identity letters in a go/no-go Navon task twice: in the morning (09:00-10:00) and early afternoon (13:00-14:00). The results showed a joint Navon effect in the morning session only, suggesting that joint attention was affected by the time-of-day effect on cognitive resources.

Comprehensive assessment of the impact of life habits on sleep disturbance, chronotype, and daytime sleepiness among high-school students

OBJECTIVE

Sleep affects adolescents in various ways. However, the effects of multiple factors on sleep hygiene remain unclear. A comprehensive assessment of the effects of life habits on sleep in high-school students was conducted.

METHODS

A cross-sectional survey of 344 high school students (age range 15-17; 171 boys, 173 girls) in Tokyo, Japan was conducted in 2015. Complete responses were provided by 294 students. Demographic variables, Pittsburgh Sleep Quality Index (PSQI), diurnal type scale, Pediatric Daytime Sleepiness Scale (PDSS), and life habits such as dinnertime, viewing electronic displays, caffeine intake, sunlight in the morning, and the brightness of the room in the night were asked.

RESULTS

The mean scores were PSQI: 5.9 (±2.3), PDSS: 19.0 (±5.8), and the diurnal type scale: 16.7 (±3.4). Using an electronic display in bed (OR = 3.01; (95%CI) 1.24-7.30), caffeine intake at night always (OR = 2.22; 1.01-4.90), and waking up before dawn (OR = 3.25; 1.34-7.88) were significantly associated with sleep disturbance. Irregular timing of the evening meal (OR = 2.06; 1.10-3.84) and display viewing within 2 h before bedtime (OR = 2.50; 1.01-6.18) or in bed (OR = 3.60; 1.41-9.21) were significantly associated with excessive daytime sleepiness. Using an electronic display within 2 h before bedtime (OR = 2.64; 1.10-6.38) or in bed (OR = 3.50; 1.40-8.76) and a living room which is bright at night (OR = 1.89; 1.06-3.36) were significantly associated with eveningness.

CONCLUSION

Each type of sleep-related problem had its own associated life habit factors.

Sensory Conflict Disrupts Activity of the Drosophila Circadian Network

Periodic changes in light and temperature synchronize the Drosophila circadian clock, but the question of how the fly brain integrates these two input pathways to set circadian time remains unanswered. We explore multisensory cue combination by testing the resilience of the circadian network to conflicting environmental inputs. We show that misaligned light and temperature cycles can lead to dramatic changes in the daily locomotor activities of wild-type flies during and after exposure to sensory conflict. This altered behavior is associated with a drastic reduction in the amplitude of PERIOD (PER) oscillations in brain clock neurons and desynchronization between light- and temperature-sensitive neuronal subgroups. The behavioral disruption depends heavily on the phase relationship between light and temperature signals. Our results represent a systematic quantification of multisensory integration in the Drosophila circadian system and lend further support to the view of the clock as a network of coupled oscillatory subunits.

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Conflicting light and temperature cycles lead to abnormal, plateau-like locomotor behavior

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Plateau-like behavior is accompanied by a collapse of the molecular circadian clock

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Temperature cues dominate during small light and temperature misalignments

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Light cues dominate during large light and temperature misalignments

Chronotype regulates the neural basis of response inhibition during the daytime

Studies have elucidated the various modulatory effects of chronotype and time-of-day on task-dependent brain activity, but it is unclear how chronotype and time-of-day regulate brain activity in response inhibition tasks. To address this question, we used functional magnetic resonance imaging (fMRI) to explore the effects of chronotype and time-of-day on response inhibition in normal day-night conditions. Morning-type (MT) and evening-type (ET) participants conducted the stop-signal task in morning (08:00-12:00 hours) and evening (19:00-23:00 hours) sessions. The results showed that inhibition-related cerebral responses in the medial frontal gyrus (MFG), middle cingulate cortex (MCC), thalamus and other typical regions for the execution of response inhibition significantly decreased from morning to evening in MT participants, whereas activity in the right inferior frontal gyrus (IFG)/insula, MFG, MCC and thalamus remained stable or increased in ET participants. The chronotypical differences in homeostatic sleep pressure may explain the observed individual differences in maintaining cognition-related cortical activation. These results suggest the importance of considering chronotype and time-of-day in the design and analysis of cognitive neuroscience studies.

Circadian preference towards morningness is associated with lower slow sleep spindle amplitude and intensity in adolescents

Individual circadian preference types and sleep EEG patterns related to spindle characteristics, have both been associated with similar cognitive and mental health phenotypes. However, no previous study has examined whether sleep spindles would differ by circadian preference. Here, we explore if spindle amplitude, density, duration or intensity differ by circadian preference and whether these associations are moderated by spindle location, frequency, and time distribution across the night. The participants (N = 170, 59% girls; mean age = 16.9, SD = 0.1 years) filled in the shortened 6-item Horne-Östberg Morningness-Eveningness Questionnaire. We performed an overnight sleep EEG at the homes of the participants. In linear mixed model analyses, we found statistically significant lower spindle amplitude and intensity in the morning as compared to intermediate (P < 0.001) and evening preference groups (P < 0.01; P > 0.06 for spindle duration and density). Spindle frequency moderated the associations (P < 0.003 for slow (<13 Hz); P > 0.2 for fast (>13 Hz)). Growth curve analyses revealed a distinct time distribution of spindles across the night by the circadian preference: both spindle amplitude and intensity decreased more towards morning in the morning preference group than in other groups. Our results indicate that circadian preference is not only affecting the sleep timing, but also associates with sleep microstructure regarding sleep spindle phenotypes.

High and low use of electronic media during nighttime before going to sleep: A comparative study between adolescents attending a morning or afternoon school shift

This study compared the effects of time spent on electronic media devices during nighttime before going to sleep on the sleep-wake cycle, daytime sleepiness, and chronotype in 568 Mexican students (288 girls, mean age = 14.08) attending a double school shift system (287 from morning shift and 281 from afternoon shift). Students completed anonymous self-report questionnaires. Results suggest that high exposure to an electronic media device may have an impact on their sleep-wake cycle, regardless of their school shift. Adolescents from the afternoon shift reported more time spent on devices. Those from the morning shift reported daytime sleepiness with the use of MP3 player, and from the afternoon shift with the use of computer, MP3 player, and television. Both school shifts reported an intermediate chronotype with all electronic media devices, but the afternoon shift with a tendency towards eveningness with the use of the computer, smartphone, and MP3 player.

State- and trait-like variation in morning and evening components of morningness-eveningness in winter depression

PURPOSE

Evening preference (eveningness) can be a risk factor for depression and a shift toward morning preference (morningness) can occur in response to treatment. A study of winter depression provides possibility to longitudinally evaluate state- and trait-like variation in morningness-eveningness during treatment in winter and remission in summer.

MATERIAL AND METHODS

Female patients with winter depression and controls without a psychiatric history (n = 54 and 32 with mean age ± standard deviation of 34.4 ± 11.0 and 35.7 ± 9.5 years, respectively) were treated with two-hour bright light for a week during winter period. Some of them (n = 40 and 19, respectively) were then restudied in summer. Measures obtained during the winter period from patients before and after treatment were compared to those obtained from controls and from the same patients in the summer period. Among compared measures, there were self-assessments of state- and trait-like differences in morning and evening components of morningness-eveningness.

RESULTS

The groups of depressed patients and controls differed in self-assessments of morning but not evening component of morningness-eveningness. The difference in state-like variation in morning component became non-significant after treatment and in summer. On the other hand, trait-like variation in this component demonstrated adequate test-retest (winter-summer) reliability, i.e. a shift toward trait-like eveningness persisted in patients in the summer.

CONCLUSIONS

The observed normalization of state-like variation in morning component of morning-evening preference can be mainly explained by the disappearance of such depressive symptoms as lack of energy, social withdrawal, loss of interest in once enjoyable activities, etc.

The cortisol awakening response after sleep deprivation: Is the cortisol awakening response a "response" to awakening or a circadian process?

This study tested whether the cortisol awakening response is dependent on the transition from sleep to awakening, or alternatively, a circadian-driven process that is independent of awakening. A total of 40 participants were randomly assigned to either a total sleep deprivation or a sleep condition. Salivary cortisol was also assessed. Participants in the sleep condition demonstrated a traditional cortisol awakening response, whereas participants in the total sleep deprivation condition showed no increases in morning cortisol. These results are consistent with the notion that if circadian-driven processes are related to the cortisol awakening response, they may only be activated when awakening occurs or is anticipated.

Nocturnal sleep mediates the relationship between morningness-eveningness preference and the sleep architecture of afternoon naps in university students

The present study investigated the parameters of nocturnal sleep that mediate the relationship between morningness-eveningness preference and the sleep architecture of naps in university students. This study had a cross-sectional, descriptive correlational design. The sleep architecture of 52 students invited to take an afternoon nap in the laboratory was recorded. The morningness-eveningness questionnaire (MEQ) was used to evaluate morningness-eveningness preference. An actigraph was used to collect students' nighttime sleep data in the week preceding the study. Polysomnography was used to measure the sleep architecture of the participants' naps. After adjustments for potential factors, although the MEQ did not directly correlate with the percentage of sleep stages in naps, the effects of the MEQ on the percentage of Stage 1 sleep, slow-wave sleep, and rapid eye movement sleep; sleep duration; and sleep efficiency of naps were mediated by the total sleep time in the preceding week. This preliminary study suggests that nap quality was affected by morningness-eveningness preference through the mediation of total nocturnal sleep time. Therefore, future studies should be carefully designed to consider nighttime sleep patterns when analyzing the effects of chronotypes on daytime sleep.

The Contribution of Neanderthals to Phenotypic Variation in Modern Humans

Assessing the genetic contribution of Neanderthals to non-disease phenotypes in modern humans has been difficult because of the absence of large cohorts for which common phenotype information is available. Using baseline phenotypes collected for 112,000 individuals by the UK Biobank, we can now elaborate on previous findings that identified associations between signatures of positive selection on Neanderthal DNA and various modern human traits but not any specific phenotypic consequences. Here, we show that Neanderthal DNA affects skin tone and hair color, height, sleeping patterns, mood, and smoking status in present-day Europeans. Interestingly, multiple Neanderthal alleles at different loci contribute to skin and hair color in present-day Europeans, and these Neanderthal alleles contribute to both lighter and darker skin tones and hair color, suggesting that Neanderthals themselves were most likely variable in these traits.

The relationship between depression and chronotype: A longitudinal assessment during childhood and adolescence

BACKGROUND/OBJECTIVE

During adolescence, chronotype shifts toward "eveningness." "Eveningness" is related to negative physical and mental health outcomes. Little is known about what influences the shift in chronotype beyond pubertal status. The current study examined the influence of earlier depression predicting later individual differences in adolescent chronotype, accounting for pubertal status, and the prospective prediction of later increases in depression from earlier chronotype.

METHODS

Youth (age M = 12.06, SD = 2.35; 56.5% girls) from the community completed repeated assessments of depression, including both self-reports (14 assessments) and diagnostic interviews (eight assessments), over a 48-month period. At the 36-month timepoint, participants completed chronotype and pubertal development measures. Regression and ANOVA analyses examined: (1) the influence of earlier depression levels (baseline to 36 months) upon chronotype, and (2) chronotype (at 36 months) upon later depression (48 months).

RESULTS

Youth with higher earlier depression symptoms (β = -0.347, P < .001) and history of depression diagnosis (β = -0.13, P = .045) showed a greater eveningness preference controlling for pubertal status, age, and gender. Further, depression diagnosis history interacted with pubertal status to predict chronotype: (F(1,243) = 4.171, P = .045) such that the influence of depression on chronotype was greatest among postpubertal youth (t = 3.271, P = .002). Chronotype (greater eveningness preference) predicted prospective increases in depression symptoms (β = -0.16, P = .03) and onset of depressive episode (b = -0.085, OR = 0.92, P = .03) 1 year later.

CONCLUSION

Depression, experienced earlier in life, predicts greater preference for eveningness, especially among postpubertal youth. In turn, later depression is predicted by evening preference. These findings suggest the reciprocal interplay between mood and biological rhythms, especially depression and chronotype, during adolescence.

Morningness-eveningness and emotion dysregulation incremental validity in predicting social anxiety dimensions

This study investigates the usefulness of morningness–eveningness and emotion dysregulation for better understanding of social anxiety dimensions. Specifically, associations between morningness–eveningness and incremental validity of emotion dysregulation as a predictor of social anxiety were examined. Data were obtained from a sample of normal students (N=510). Results of regression analyses showed that morningness was a significant predictor of social anxiety variables. Dimensions of emotion dysregulation had multiple associations with facets from social anxiety. Emotion dysregulation was found to be a positive predictor of social anxiety. The results expand the understanding of social anxiety and indicate how the domains of morningness–eveningness and emotion regulation could explain social anxiety in a normal population.

Chronotype Differences in Health Behaviors and Health-Related Quality of Life: A Population-Based Study Among Aged and Older Adults

This study investigates health behaviors, health-related quality of life (HRQOL) and sleep among chronotypes in a community-based sample (n = 2,976). Analysis of covariance indicated evening types (E-types) had a significantly higher percentage of current smokers and more sleep-interfering behaviors compared to intermediate and morning types (M-type), and also lower physical activity and more sleep disturbance compared to M-types. E-types also had worse mental HRQOL compared to both chronotypes, and worse physical HRQOL compared to M-types. Exploratory analyses indicated E-types consumed more caffeinated beverages at night, smoked or ate heavy meals before bedtime, kept irregular sleep-wake schedules, and took more naps. Mediational analyses indicated that sleep-interfering behavior partially mediated the relationship between chronotype and sleep disturbance, and physical activity partially mediated the relationship between chronotype and mental HRQOL. E-types had more unhealthy behaviors, which may subsequently place them at higher risk for health problems.

Self-reported discomfort associated with Daylight Saving Time in Brazilian tropical and subtropical zones

BACKGROUND

Daylight Saving Time (DST) annually moves clocks 1 hour forward, when daytime is longer than night. Previous studies from medium and high latitude locations have pointed to a disruptive effect of DST on human circadian rhythms. Since Brazil is an equatorial country implementing DST, a different relationship between photic and social synchronisers may interfere with DST effects.

AIM

To explore the prevalence and duration of self-reported discomfort related to DST among Brazilian residents (latitude 12-33° S, longditude 39-57° W). It was hypothesised that an elevated prevalence of self-reported discomfort would be found in Brazil, due to the pronounced uncoupling between social and geophysical synchronisers.

SUBJECTS AND METHODS

In total, 12 467 volunteers completed a web-based, Brazilian version of Horne-Östberg Morningness-Eveningness Questionnaire, provided demographic information, and answered questions related to DST complaints (discomfort, duration of discomfort).

RESULTS

Of the total sample, 45.43% reported no discomfort related to DST, with meaningful proportions for all chronotypes. However, eveningness was most associated with discomfort. About one fourth of the total sample reported discomfort over the whole DST period. Gender interaction is largely supported by these results.

CONCLUSIONS

DST at low latitude locations may be disruptive for circadian rhythms, since seasonality of sunrise near the equator is negligible or very mild.

The relationship between chronotype and depressive symptoms: A meta-analysis

BACKGROUND

Expanding our understanding of the factors that influence depression is crucial for prognosis and treatment. In light of increasing evidence of an association between disrupted circadian rhythms and affective symptoms, a meta-analysis was used to examine the relationship between an eveningness chronotype and depression.

METHODS

Electronic searches of the PsycINFO, Medline, Scopus, and Google Scholar databases were conducted in February 2016. Relevant reviews, related journals, and reference lists were manually searched. Statistical data were reported or transformed to a Fisher's z correlational coefficient for effect size analysis.

RESULTS

Data from 36 studies (n =15734) met the inclusion criteria and were analysed under a random effects model. Nearly all included studies utilised the Composite Scale of Morningness (CSM) or the Morningness-Eveningness Questionnaire (MEQ) as a measure of chronotype. Overall effect size from 58 effect sizes was small (z=-.20; 95% CI: -.18 to -.23). Effect sizes based on the CSM were significantly larger than those based on the MEQ. There was no evidence of publication bias.

LIMITATIONS

The number of studies comparing different mood disorders or the potential moderating effects of gender and age were too few to draw conclusions regarding their respective effect sizes. Future research should utilise longitudinal designs to draw causal inferences on the directionality of this relationship.

CONCLUSIONS

Findings from this meta-analysis indicate an eveningness orientation is somewhat associated with more severe mood symptoms. Chronobiological approaches may contribute to the prevention and treatment of depressive disorders.

What #theDress reveals about the role of illumination priors in color perception and color constancy

The disagreement between people who named #theDress (the Internet phenomenon of 2015) "blue and black" versus "white and gold" is thought to be caused by individual differences in color constancy. It is hypothesized that observers infer different incident illuminations, relying on illumination "priors" to overcome the ambiguity of the image. Different experiences may drive the formation of different illumination priors, and these may be indicated by differences in chronotype. We assess this hypothesis, asking whether matches to perceived illumination in the image and/or perceived dress colors relate to scores on the morningness-eveningness questionnaire (a measure of chronotype). We find moderate correlations between chronotype and illumination matches (morning types giving bluer illumination matches than evening types) and chronotype and dress body matches, but these are significant only at the 10% level. Further, although inferred illumination chromaticity in the image explains variation in the color matches to the dress (confirming the color constancy hypothesis), color constancy thresholds obtained using an established illumination discrimination task are not related to dress color perception. We also find achromatic settings depend on luminance, suggesting that subjective white point differences may explain the variation in dress color perception only if settings are made at individually tailored luminance levels. The results of such achromatic settings are inconsistent with their assumed correspondence to perceived illumination. Finally, our results suggest that perception and naming are disconnected, with observers reporting different color names for the dress photograph and their isolated color matches, the latter best capturing the variation in the matches.

Correcting delayed circadian phase with bright light therapy predicts improvement in ADHD symptoms: A pilot study

Attention-deficit/hyperactivity disorder (ADHD) is a common condition with comorbid insomnia reported in >70% of children and adults. These patients demonstrate delays in sleep-wake rhythms, nocturnal rise in melatonin, and early morning rise in cortisol. Given that standard psychopharmacologic treatments for ADHD often do not completely control symptoms in participants with circadian rhythm delay, we sought to test whether bright light therapy (BLT) advances circadian rhythms and further reduces ADHD symptoms over standard treatments. In addition to standard of care, participants with ADHD diagnosis underwent 1 week of baseline assessment followed by 2-weeks of 30-min morning 10,000-lux BLT beginning 3 h after mid-sleep time. Participants minimized overhead light after 4 p.m., wore an actigraphy watch, and recorded BLT time on daily sleep logs. Dim Light Melatonin Onset (DLMO) was assessed at baseline and after 2-week treatment. ADHD symptoms were measured by the ADHD-Rating Scales (ADHD-RS). BLT significantly advanced the phase of DLMO by 31 min [mean time (SEM), 20:36 (0:21) advanced to 20:05 (0:20)] and mid-sleep time by 57 min [4:37 (0:22) advanced to 3:40 (0:16); paired t-tests, p = 0.002 and 0.004, respectively). Phase advances (in DLMO or mid-sleep time) were significantly correlated with decreased ADHD-RS total scores (p = 0.027 and 0.044) and Hyperactive-Impulsive sub-scores (p = 0.014 and 0.013, respectively). Actigraphy analysis for a subset of 8 participants with significant DLMO phase advance revealed no significant changes in total sleep time, sleep efficiency, wake after sleep onset, or percent wake during sleep interval. This is the first successful use of BLT for advancing melatonin phase and improving ADHD symptoms in adults. BLT may be a complementary treatment for both delayed sleep timing and ADHD symptoms in adults.

Associations between chronotypes and psychological vulnerability factors of depression

Chronotypes have been associated with psychopathology. The eveningness chronotype has been consistently linked with depressed states or depressive disorder, but the underlying mechanism remains unclear. Prior studies have shown associations between chronotype and personality traits that are linked to depression (e.g. neuroticism), but other psychological vulnerability factors have not been previously investigated in relation to chronotypes. The aim of this study was to examine the association between chronotypes, depression and psychological risk factors of depression (namely, cognitive reactivity and worry), in a large cohort of depressed patients and healthy individuals. We used data from the Netherlands Study of Depression and Anxiety (n = 1654), which includes 1227 clinically diagnosed individuals with a lifetime diagnosis of depression and 427 healthy controls. We assessed cognitive reactivity (Leiden Index of Depression Sensitivity-Revised) and trait worry (Penn State Worry Questionnaire). We controlled for sociodemographic factors as well as for insomnia and neuroticism. We found that the evening type is associated with higher cognitive reactivity scores, especially with increased rumination. Cognitive reactivity also mediated the relationship between chronotype and depression status, even when controlling for neuroticism and insomnia. Trait worry was not associated with chronotype. Our findings show that depressogenic cognitions are more prevalent in evening types and perhaps mediate the association between chronotype and depression. Further prospective research is needed to determine the timeline of the association. Nevertheless, results imply that targeting depressogenic cognitive processes, perhaps in combination with chronotherapeutic treatments, may be particularly useful in evening types.

What predicts inattention in adolescents? An experience-sampling study comparing chronotype, subjective, and objective sleep parameters

OBJECTIVE

Many adolescents sleep insufficiently, which may negatively affect their functioning during the day. To improve sleep interventions, we need a better understanding of the specific sleep-related parameters that predict poor functioning. We investigated to which extent subjective and objective parameters of sleep in the preceding night (state parameters) and the trait variable chronotype predict daytime inattention as an indicator of poor functioning.

METHODS

We conducted an experience-sampling study over one week with 61 adolescents (30 girls, 31 boys; mean age = 15.5 years, standard deviation = 1.1 years). Participants rated their inattention two times each day (morning, afternoon) on a smartphone. Subjective sleep parameters (feeling rested, positive affect upon awakening) were assessed each morning on the smartphone. Objective sleep parameters (total sleep time, sleep efficiency, wake after sleep onset) were assessed with a permanently worn actigraph. Chronotype was assessed with a self-rated questionnaire at baseline. We tested the effect of subjective and objective state parameters of sleep on daytime inattention, using multilevel multiple regressions. Then, we tested whether the putative effect of the trait parameter chronotype on inattention is mediated through state sleep parameters, again using multilevel regressions.

RESULTS

We found that short sleep time, but no other state sleep parameter, predicted inattention to a small effect. As expected, the trait parameter chronotype also predicted inattention: morningness was associated with less inattention. However, this association was not mediated by state sleep parameters.

CONCLUSIONS

Our results indicate that short sleep time causes inattention in adolescents. Extended sleep time might thus alleviate inattention to some extent. However, it cannot alleviate the effect of being an 'owl'.

Ratings of Perceived Exertion and Self-reported Mood State in Response to High Intensity Interval Training. A Crossover Study on the Effect of Chronotype

The aim of this study was to investigate the influence of chronotype on mood state and ratings of perceived exertion (RPE) before and in response to acute high intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness–eveningness questionnaire, 12 morning-types (M-types; N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg) and 11 evening-types (E-types; N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg) were enrolled in a randomized crossover study. All subjects underwent measurements of Profile of Mood States (POMS), before (PRE), after 12 (POST12) and 24 h (POST24) the completion of both morning (08.00 am) and evening (08.00 p.m.) training. Additionally, Global Mood Disturbance and Energy Index (EI) were calculated. RPE was obtained PRE and 30 min POST HIIE. Two-way ANOVA with Tukey’s multiple comparisons test of POMS parameters during morning training showed significant differences in fatigue, vigor and EI at PRE and POST24 between M-types and E-types. In addition, significant chronotype differences were found only in POST12 after the evening HIIE for fatigue, vigor and EI. For what concerns Borg perceived exertion, comparing morning versus evening values in PRE condition, a higher RPE was observed in relation to evening training for M-types (P = 0.0107) while E-types showed higher RPE values in the morning (P = 0.008). Finally, intragroup differences showed that E-types had a higher RPE respect to M-types before (P = 0.002) and after 30 min (P = 0.042) the morning session of HIIE. No significant changes during the evening training session were found. In conclusion, chronotype seems to significantly influence fatigue values, perceived exertions and vigor in relation to HIIE performed at different times of the day. Specifically, E-types will meet more of a burden when undertaking a physical task early in the day. Practical results suggest that performing a HIIE at those times of day that do not correspond to subjects’ circadian preference can lead to increased mood disturbances and perceived exertion. Therefore, an athlete’s chronotype should be taken into account when scheduling HIIE.

Trial registration:

ACTRN12617000432314, registered 24 March 2017, “retrospectively registered”.

Web address of trial:

https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=371862&showOriginal=true&isReview=true

ARNTL, CLOCK and PER3 polymorphisms - links with chronotype and affective dimensions

Recently, seven single nucleotide polymorphisms (SNPs) of ARNTL, TIM and PER3 genes were found associated with affective temperaments in bipolar disorder patients. This study aimed to test whether a) the same associations appear in a non-clinical sample; b) the SNPs are related to other affective dimensions; c) the SNPs underpin the associations between chronotype and affective temperaments/dimensions. Three hundred thirty-eight university students completed the Temperament Scale of Memphis, Pisa, Paris and San Diego Auto-questionnaire, the Centre for Epidemiological Studies Depression Scale, the Perceived Stress Scale, the General Health Questionnaire, the Seasonal Pattern Assessment Questionnaire and the Composite Scale of Morningness. Seven SNPs of the ARNTL, TIM and PER3 genes were genotyped. According to nominal significance, ARNTL rs7107287 was associated with a cyclothymic temperament, depressive and stress symptoms, general mental health and perceived negative impact of seasonality, while TIM rs10876890 was associated with a hyperthymic temperament, and the TIM rs2291738 was associated with chronotype. Different SNPs were related to chronotype and affective temperaments/dimensions, and therefore, they seem to not underpin relationships between chronotype and affective dysfunction, that is, in the present study, eveningness was related to dysthymic, cyclothymic and irritable temperaments, more symptoms of depression, stress, worse mental health and a negative impact of seasonality, while morningness was related to hyperthymic temperament. The SNPs associations need further replication given that they did not achieve Bonferroni criteria of significance accounting for the number of polymorphisms considered and tests conducted.

Sleep Disorders: Assessment and Treatment in Preschool-Aged Children

Sleep issues are common in preschoolers, defined in this article as ages 3 to 5 years. Sleep deprivation can cause behavioral and cognitive issues. Sleep issues seen in the preschool years include insomnia, obstructive sleep apnea, parasomnias, and restless legs syndrome. Sleep issues seem to exacerbate mood and attention disturbances. Conversely, children with psychiatric disorders are likely to have sleep problems. Treatment of sleep issues is important for long-term mental health and optimization of functioning.

Conscientiousness but not agreeableness mediates females' tendency toward being a morning person

Individuals differ in their chronotype, and some are identified as morning ones and others as evening ones. Earlier studies showed that women were higher on morningness, conscientiousness, and agreeableness. In this study, we aimed at exploring the mediational effects of conscientiousness and agreeableness in the relationship of gender and morningness-eveningness. Participants were 669 university students. Results supported positive relationships between morningness and conscientiousness and agreeableness and between conscientiousness and agreeableness. Females were higher on all these three variables. Mediation analyses suggested that the effect of gender (here females) on chronotype (here morningness) was mediated by conscientiousness but not agreeableness so that after the mediation partially occurred, the gender's effect did not remain significant anymore. This study backed our hypothesis that conscientiousness might play a more pronounced role than the intrinsic diurnal rhythm concerning the sex differences in chronotype.

Sleep quality, chronotype, temperament and bipolar features as predictors of depressive symptoms among medical students

The assessment of risk factors is a crucial step in the prevention and treatment of affective disorders and should encompass personal dispositions. The aim of this study was to assess the value of chronotype and temperament as independent predictors of depressive symptoms among medical students. The study surveyed 140 students of the Faculty of Medicine with a battery of questionnaires: the Beck Depression Index (BDI), Hypomania Checklist 32 (HCL-32), Pittsburgh Sleep Quality Index (PSQI), Chronotype Questionnaire and Eysenck Personality Questionnaire Revised. The results were tested using Pearson's correlation quotient and general linear model. Ten percent of the participants demonstrated a BDI score suggestive of clinically significant depressive symptoms. BDI score correlated positively with HCL-32 score. A rise in BDI was independently predicted by elevated Neuroticism and PSQI scores and morningness. Those effects were independent from each other and from other parameters of the model. The presence of depressive symptoms might be associated with bipolar features among medical students. Poor sleep quality predicted depressive symptoms, similarly to Neuroticism and independently of temperament and chronotype. Future studies on the associations between personal dispositions and mood disorders among medical students are required to help identify those at greater risk of developing affective illness. Effective prophylaxis and early intervention are warranted to ensure better treatment results.

Differences in morning-evening type and sleep duration between Black and White adults: Results from a propensity-matched UK Biobank sample

Biological evidence suggests that ethno-racial differences in morning-evening type are possible, whereby Blacks may be more likely to be morning type compared to Whites. However, population-level evidence of ethno-racial difference in morning-evening type is limited. In an earlier study, we reported that morning type was more prevalent in Blacks compared to Whites in the United Kingdom (UK) Biobank cohort (N = 439 933). This study aimed to determine if these ethno-racial differences persisted after accounting for an even broader range of social, environmental and individual characteristics and employing an analytic approach that simulates randomization in observational data, propensity score modeling. Data from UK Biobank participants whose self-identified race/ethnicity was Black/Black British or White; who did not report daytime napping, shift work or night shift work; who provided full mental health information; and who were identified using propensity score matching were used (N = 2044). Each sample was strongly matched across all social, environmental and individual characteristics as indicated by absolute standardized mean differences <0.09 for all variables. The prevalence of reporting nocturnal short, adequate and long sleep as well as morning, intermediate and evening type among Blacks (n = 1022) was compared with a matched sample of Whites (n = 1022) using multinomial logistic regression models. Blacks had a 62% greater odds of being morning type [odds ratio (OR) = 1.620, 95% confidence interval (CI): 1.336-1.964, p < .0001] and a more than threefold greater odds of reporting nocturnal short sleep (OR = 3.453, 95% CI: 2.846-4.190, p < .0001) than Whites. These data indicate that the greater prevalence of morning type and short nocturnal sleep in Blacks compared to Whites is not fully explained by a wide range of social and environmental factors. If sleep is an upstream determinant of health, these data suggest that ethno-racially targeted public health sleep intervention strategies are needed.

Spanish Adaptation of the Morningness-Eveningness-Stability-Scale improved (MESSi)

The aim of the present study was to conduct the preliminary adaptation of the Morningness-Eveningness-Stability-Scale improved (MESSi) to Spanish population, testing its factor structure and construct validity. Participants were 261 adults (65% women;M= 31.4,SD= 12.01) who filled out measures of Morningness-Eveningness (MESSi and CSM), sleep habits, personality traits, positive and negative affect, and subjective level of alertness during the day. Psychometric results supported a three factorial model with the factors Morning Affect, Eveningness and Distinctness (RMSEA = .072). The factors showed good internal consistence (α = 0.72–0.85). The pattern of correlations between MESSi and the other measures were in the expected direction (low to moderated size effects). Morning Affect was positively predicted by morning chronotype (R2= .64), Eveningness was negatively predicted by age and positively by evening chronotype (R2= .41), and Distinctness was negatively predicted by sex (women reported higher DI than men) and age (R2= .08). This study provides evidence for the factor structure of a new measure of Morningness-Eveningness based on a rigorous psychometric evaluation.

Relationship between chronotype and temperament/character among university students

Chronotype is largely classified as being morning or evening types according to preference for daily activity and the preferred bedtime. This study examined the relationship between chronotype and temperament/character dimensions among university students. A total of 2857 participants completed the 140-item Temperament and Character Inventory-Revised Short version (TCI-RS) from a 5-score scale as well as the 13-item composite scale for morningness-eveningness (CSM). In this study, we classified chronotype as "morning," "neither," or "evening" types according to CSM scores and compared the scores in terms of 4 temperament dimensions and 3 character dimensions. The evening type showed high values for novelty seeking and harm avoidance, whereas the morning type had high scores for persistence, self-directedness, and cooperativeness. A logistic regression analysis after controlling for age and gender showed that chronotype significantly associated with persistence and novelty seeking. The results of this study suggest that chronotype is different according to gender and age and in addition, chronotype closely correlates with temperament and character. Among these, eveningness was associated with high novelty seeking, whereas morningness was associated with high persistence. Further studies are required to investigate the relationship between chronotype and temperament/character dimensions in a wider age bracket.

Differential effects of circadian typology on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience

Various physiological and psychological functions are influenced by circadian typology (CT), which was reported to be related to resilience. However, few studies have assessed the effects of CT in relation to resilience. The aim of the present study was to assess the influence of CT on sleep-related symptoms, physical fatigue and psychological well-being in relation to resilience. The present study included a total of 1794 healthy hospital employees, and they completed the Morningness-Eveningness Questionnaire, Connor-Davidson Resilience Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Fatigue Severity Scale, Hospital Anxiety and Depression Scale and World Health Organization Quality of Life Scale Abbreviated Version. Subjects with evening type showed lower sleep quality, more daytime sleepiness and physical fatigue than neither types and morning types. Additionally, evening types were more depressed and anxious and reported a poorer quality of life. CT was found to be a significant predictor of sleep quality, but CT was minimally associated with physical fatigue and psychological well-being in the regression analysis. Instead, resilience was substantially related to all of the variables measured. In conclusion, CT independently predicts sleep quality, but the effects of CT on physical fatigue and psychological well-being are negligible compared to those of resilience.

Sleep Phase Delay in Cystic Fibrosis: A Potential New Manifestation of Cystic Fibrosis Transmembrane Regulator Dysfunction

BACKGROUND

Cystic fibrosis (CF) transmembrane regulator (CFTR) protein dysfunction causes CF. Improving survival allows detection of increasingly subtle disease manifestations. CFTR dysfunction in the central nervous system (CNS) may disturb circadian rhythm and thus sleep phase. We studied sleep in adults to better understand potential CNS CFTR dysfunction.

METHODS

We recruited participants from April 2012 through April 2015 and administered the Munich Chronotype Questionnaire (MCTQ). We compared free-day sleep measurements between CF and non-CF participants and investigated associations with CF survival predictors.

RESULTS

We recruited 23 female and 22 male adults with CF aged 18 to 46 years and 26 female and 22 male volunteers aged 18 to 45 years. Compared with volunteers without CF, patients with CF had delayed sleep onset (0.612 h; P = .015), midsleep (1.11 h; P < .001), and wake (1.15 h; P < .001) times and prolonged sleep latency (7.21 min; P = .05) and duration (0.489 h; P = .05). Every hour delay in sleep onset was associated with shorter sleep duration by 0.29 h in patients with CF and 0.75 h in subjects without CF (P = .007) and longer sleep latency by 7.51 min in patients with CF and 1.6 min in volunteers without CF (P = .035). Among patients with CF, FEV₁ % predicted, prior acute pulmonary exacerbations, and weight were independent of all free-day sleep measurements.

CONCLUSIONS

CF in adults is associated with marked delays in sleep phase consistent with circadian rhythm phase delays. Independence from disease characteristics predictive of survival suggests that sleep phase delay is a primary manifestation of CFTR dysfunction in the CNS.

From Lark to Owl: developmental changes in morningness-eveningness from new-borns to early adulthood

Morningness-eveningness or chronotype changes significantly throughout the life span. This has been reported for the transition during adolescence in some studies, and to a lesser extent in early adulthood. Primary and pre-school children have been under investigation in fewer studies. This is the first comprehensive study covering the age range from very young children until early adulthood (0-30 years) based on the same measurement instrument. Here, we show that the turn towards eveningness starts at an early age in German children. Based on 26,214 cross-sectional data, we further show that at the end of adolescence, morningness-eveningness does not significantly change during early adulthood. Sex differences arise during puberty and remain until 30 years. The breaking point for the turn towards morningness is 15.7 years in girls and 17.2 boys. At the age of 0-1 years, there are about 70% morning types, and about 1% evening types, while at the age of 16 years, only 5% are morning types and 19% are evening types.