The circadian preferences in the context of sociodemographic indicators and lifestyle.

Circadian preferences are frequently used as a synonym for chronotype. Both terms are based on different principles and are measured by a variant questionnaire. We focused on circadian preferences, delimited as an individual preference for the timing of various activities, and their relationship to the selected sociodemographic factors. All participants (n = 2068) filled out online questionnaires including MEQ, MCTQ, and sociodemographic information (age, sex, place of residence, marital status, childcare, education, financial security, physical and mental health). Although the concept of chronotype and circadian preference differ, the mutual correlation was high. Our results of the observed variables are similar to other studies. We revealed evening preference is related to a higher probability of living in a big city, having a single life, a higher risk of smoking, worse health status, and worse financial security. We observed a higher social jet lag among them. Our research complies with previous studies, which found that in some areas, people with evening preferences evince worse results. Due to the evening preference, these people are at a disadvantage, and the society's setting for morning operations can lead to a deepening of these differences. We recommend further research, which would focus on the practical application of results to the everyday life of participants to create preventive programs aimed at reducing the negative impact of evening preferences on life.

Human chronotype: Comparison of questionnaires and wrist-worn actigraphy.

In this work, we investigated the accuracy of chronotype estimation from actigraphy while evaluating the required recording length and stability over time. Chronotypes have an important role in chronobiological and sleep research. In outpatient studies, chronotypes are typically evaluated by questionnaires. Alternatively, actigraphy provides potential means for measuring chronotype characteristics objectively, which opens many applications in chronobiology research. However, studies providing objective, critical evaluation of agreement between questionnaire-based and actigraphy-based chronotypes are lacking. We recorded 3-months of actigraphy and collected Morningness-Eveningness Questionnaire (MEQ), and Munich Chronotype Questionnaire (MCTQ) results from 122 women. Regression models were applied to evaluate the questionnaire-based chronotypes scores using selected actigraphy features. Changes in predictive strength were evaluated based on actigraphy recordings of different duration. The actigraphy was significantly associated with the questionnaire-based chronotype, and the best single-feature-based models explained 37% of the variability (R2) for MEQ (p < .001), 47% for mid-sleep time MCTQ-MSFsc (p < .001), and 19% for social jetlag MCTQ-SJLrel (p < .001). Concerning stability in time, the Mid-sleep and Acrophase features showed high levels of stability (test-retest R ~ 0.8), and actigraphy-based MSFscacti and SJLrelacti showed high temporal variability (test-retest R ~ 0.45). Concerning required recording length, features estimated from recordings with 3-week and longer observation periods had sufficient predictive power on unseen data. Additionally, our data showed that the subjectively reported extremes of the MEQ, MCTQ-MSFsc, and MCTQ-SJLrel are commonly overestimated compared to objective activity peak and middle of sleep differences measured by actigraphy. Such difference may be associated with chronotype time-variation. As actigraphy is considered accurate in sleep-wake cycle detection, we conclude that actigraphy-based chronotyping is appropriate for large-scale studies, especially where higher temporal variability in chronotype is expected.

Reliability and Validity of the Czech Version of the Pittsburgh Sleep Quality Index in Patients with Sleep Disorders and Healthy Controls.

OBJECTIVES: Psychometric properties of the Czech version of the Pittsburgh Sleep Quality Index (PSQI-CZ) have been evaluated only in patients with chronic insomnia, and thus, it is unclear whether PSQI-CZ is suitable for use in other clinical and nonclinical populations. This study was aimed at examining the validity and reliability of the PSQI-CZ and at assessing whether the unidimensional or multidimensional scoring of the instrument would be recommended. METHODS: A total of 524 adult subjects from the Czech population participated in the study. The internal consistency of PSQI was evaluated using Cronbach's alpha. The known-group validity was tested using the Kruskal-Wallis H test to verify the difference between patients with sleep disorders and healthy control sample. For testing the structural validity, a cross-validation approach was used with both exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). For EFA, the maximum likelihood method with direct oblimin rotation and parallel analysis was used. RESULTS: The internal consistency of PSQI-CZ items was moderate (α = 0.75). Receiver operating characteristic (ROC) curve analysis showed high specificity (0.79) and moderate sensitivity (0.64) using an optimal cut-off score of 10. The EFA revealed a 3-factor structure with factors labelled as "sleep duration and efficiency," "sleep disturbances and quality," and "sleep latency." The CFA showed that the emerged 3-factor model had a partly acceptable fit, which was better than other previously supported models. CONCLUSIONS: A high cut-off score of 10 is recommended to define poor sleep quality. Given the inconsistency of structural analyses, alternative scoring was not recommended. However, the individual components in addition to a total score should be interpreted when assessing sleep quality. We recommend editing and verifying the PSQI-CZ translation.

Comparison of Munich Chronotype Questionnaire (MCTQ) and Morningness-Eveningness Questionnaire (MEQ) Czech version.

A chronotype is a designation for individual preference of times for different activities in humans. In chronobiological research, it can be measured in many ways, including subjective questionnaires. The most frequently used questionnaires for determining the chronotype are Morningness-Eveningness Questionnaire (MEQ) and Munich Chronotype Questionnaire (MCTQ). Many studies from around the world have already reported metric properties of the MEQ and MCTQ and their relationship in different languages. In this study, we created the Czech version of the MCTQ and examined its relationship with the Czech version of MEQ, including socio-demographic effects. We also examined the ability of the MCTQ to identify chronotypes and cutoffs for their determination. In total, 2703 people (1964 females, 739 males, 18-75 years of age) were screened by the MEQ, MCTQ and reported on age, sex and self-declared body mass index (BMI). We found a significant relationship (p < .001) between MEQ and MCTQ (MSFsc score, used as a chronotype indicator). No significant sex differences in MEQ and in MSFsc were found, but the relationship between age and MSFsc (mid-sleep on free days corrected for sleep debt on weekdays) (p < .001), MEQ (p < .001), social jet-lag (SJL, p < .001) and BMI (p < .001) were found. The SJL was related to MSFsc (p < .001), MEQ (p < .001) and BMI (p < .05). The optimal cutoff value of MSFsc to identify morning and evening chronotype was 3.35 and 4.6, respectively. The results of this study support the mutual substitutability of the Czech version of MEQ and MCTQ.

Subjective-objective sleep discrepancy in patients with insomnia during and after cognitive behavioural therapy: An actigraphy study.

Although patients with insomnia often show a discrepancy between self-reported and objective sleep parameters, the role of and change in this phenomenon during treatment remain unclear. The present study aimed to assess the effect of cognitive behavioural therapy for insomnia on subjective and objective sleep discrepancy of total sleep time, sleep-onset latency and wake after sleep onset. The total sleep time discrepancy was also assessed across the entire therapy. The second aim was to examine the treatment outcome of two insomnia groups differing in sleep perception. Thirty-six adults with insomnia (mean age = 46.7 years, SD = 13.9; 22 females) were enrolled in the final analyses. Patients underwent a 6-week group cognitive behavioural therapy for insomnia programme. Sleep diary and actigraphy measurements were obtained during the therapy. Patients who underestimated total sleep time (n = 16; underestimating group) were compared with patients who accurately perceived or overestimated total sleep time (n = 20; accurate/overestimating group). After cognitive behavioural therapy for insomnia, a significant decrease of total sleep time and sleep-onset latency discrepancy was observed without a change in wake after sleep onset discrepancy in the total sample. Only the underestimating group reported decreased sleep-onset latency discrepancy after the treatment, whereas total sleep time discrepancy significantly changed in both groups. The underestimating group showed a significant decrease of total sleep time discrepancy from Week 1 to Week 2 when the sleep restriction was implemented, whereas the accurate/overestimating group showed the first significant change at Week 4. In conclusion, both groups differing in sleep perception responded similarly to cognitive behavioural therapy for insomnia, although different In conclusion, both groups differing in sleep perception responded similarly to cognitive behavioural therapy for insomnia, although different therapeutic components could play important roles in each group. components could play important roles in each group.

Evening and night exposure to screens of media devices and its association with subjectively perceived sleep: Should "light hygiene" be given more attention?

OBJECTIVE: The aim of the study was to examine subjective sleep quality in a population of healthy volunteers and its association with evening and night light exposure to screens of media devices. METHODS: A total of 693 participants (mean age 31.2±11.4 years, 159 men, and 538 women) completed an online questionnaire battery consisting of several sleep-related questionnaires: PSQI, FSS, MCTQ, MEQ, and added questions assessing the timing and character the evening and night exposure to electronical devices (TV, PC, tablets, and phones), and the use of various filters blocking short-wavelength light. RESULTS: Statistical analyses show that longer cumulative exposure to screen light in the evening was associated with greater sleep inertia in the morning (P = .019, η2=0.141) and longer sleep latency on workdays P = .038, η2=0.135). Furthermore, exposure to screen light 1.5 h before sleep or during night awakenings was also associated with a decreased chance to wake up before alarm clock (P = .003, d=0.30), larger social jet lag (P < .001, d=0.15), more daytime dysfunction (P < .001, d=0.40), decreased subjective sleep quality (P = .024, d=0.16), and more fatigue (P < .001, d=0.52). A statistical trend for an increase in duration of sleep on weekdays (P = .058, d=0.23) was also found in participants using blue-light filters in the evening hours. DISCUSSION: Our results are in line with other studies that converge to show the negative association of evening and night exposure to short-wavelength light on subjective and objective sleep parameters. Results suggest that light hygiene in general population should be given more attention not only in the context of clinical sleep medicine but also in the realm of public health.

Cross-sectional and within-subject seasonality and regularity of hospitalizations: A population study in mood disorders and schizophrenia.

BACKGROUND: Seasonal peaks in hospitalizations for mood disorders and schizophrenia are well recognized and often replicated. The within-subject tendency to experience illness episodes in the same season, that is, seasonal course, is much less established, as certain individuals may temporarily meet criteria for seasonal course purely by chance. AIMS: In this population, prospective cohort study, we investigated whether between and within-subject seasonal patterns of hospitalizations occurred more frequently than would be expected by chance. METHODS: Using a compulsory, standardized national register of hospitalizations, we analyzed all admissions for mood disorders and schizophrenia in the Czech Republic between 1994 and 2013. We used bootstrap tests to compare the observed numbers of (a) participants with seasonal/regular course and (b) hospitalizations in individual months against empirical distributions obtained by simulations. RESULTS: Among 87 184 participants, we found uneven distribution of hospitalizations, with hospitalization peaks for depression in April and November (X2 (11) = 363.66, P < .001), for mania in August (X2 (11) = 50.36, P < .001) and for schizophrenia in June (X2 (11) = 70.34, P < .001). Significantly more participants than would be expected by chance, had two subsequent rehospitalizations in the same 90 days in different years (7.36%, bootstrap P < .01) or after a regular, but non-seasonal interval (6.07%, bootstrap P < .001). The proportion of participants with two consecutive hospitalizations in the same season was below chance level (7.06%). CONCLUSIONS: Psychiatric hospitalizations were unevenly distributed throughout the year (cross-sectional seasonality), with evidence for regularity, but not seasonality of hospitalizations within subjects. Our data do not support the validity of seasonal pattern specifier. Season may be a general risk factor, which increases the risk of hospitalizations across psychiatric participants.

Block the light and sleep well: Evening blue light filtration as a part of cognitive behavioral therapy for insomnia.

The objective of the present study was to assess the effect of combining CBT-I with wearing blue-light blocking glasses 90 min prior to bedtime on subjective and objective sleep parameters and daily symptoms (anxiety, depression, hyperarousal). Thirty patients (mean age 48.1 ± 16.13 years, range 21-71, 15 men/15 women) completed a CBT-I group therapy program, with groups randomly assigned to either "active" (blue-light filtering glasses) condition or "placebo" (glasses without filtering properties) condition. Patients were continually monitored by wristwatch actigraphy, kept their sleep diaries and completed a standard questionnaire battery at admission and after the end of the program. Statistical analyses showed a greater reduction of BAI score in "active" (4.33 ± 4.58) versus "placebo" (-0.92 ± 3.68) groups of patients [F = 6.389, p = .019, Cohen's d = 1.26] and significant prolongation of subjective total sleep time in "active" (-36.88 ± 48.68 min.) versus "placebo" (7.04 ± 47.50 min.) [F = 8.56, p < .01, d = 0.91] group. When pre- and post-treatment results were compared in both groups separately, using paired-samples t-tests, significant differences were observed also in the active group for BDI-II score (t = 3.66, p = .003, Cohen's d = 0.95) and HAS score (t = 2.90, p = .012, Cohen's d = 0.75). No significant differences were found in the placebo group. In active group, there was also a significant reduction of subjective sleep latency (t = 2.65, p = .021, d = 0.73) and an increase of subjective total sleep time (t = -2.73, p = .018, d = -0.76) without change in objective sleep duration which was significantly shortened in the placebo group. We provide further evidence that blocking short-wavelength light in the evening hours may be beneficial for patients suffering from insomnia.

Weight loss in conservative treatment of obesity in women is associated with physical activity and circadian phenotype: a longitudinal observational study.

INTRODUCTION: The study investigates the association between circadian phenotype (CP), its stability (interdaily stability - IS) and physical activity (PA) in a weight loss (WL) programme. METHODS: Seventy-five women in WL conservative treatment (BMI ≥ 25 kg/m2) were measured (for about 3 months in between 2016 and 2018) by actigraphy. RESULTS: We observed a difference in time of acrophase (p = 0.049), but no difference in IS (p = 0.533) between women who lost and did not lose weight. There was a difference in PA (mesor) between groups of women who lost weight compared to those who gained weight (p = 0.007). There was a relationship between IS and PA parametres mesor: p0.001; and the most active 10 h of a day (M10): p < 0.001 - the more stable were women in their rhythm, the more PA they have. Besides confirming a relationship between PA and WL, we also found a relation between WL and CP based on acrophase. Although no direct relationship was found for the indicators of rhythm stability (IS), they can be considered very important variables because of their close connection to PA - a main factor that contributes to the success of the WL programme. DISCUSSION: According to the results of the study, screening of the CP and its stability may be beneficial in the creation of an individualized WL plan.

Decreased need for sleep as an endophenotype of bipolar disorder: an actigraphy study.

Reports of subjective sleep impairments have been replicated in adults with bipolar disorder (BD), young BD patients, and even children of parents with BD. Furthermore, circadian rhythm alterations are a core feature of BD. Despite the impairment in circadian rhythms and altered sleep included in various heuristic developmental models of BD, thus far, biomarkers have not been sufficiently objectively validated. Thus, here, we assessed the rest-activity circadian rhythmicity and sleep macrostructure using actigraphy in a sample of unaffected child and adolescent offspring of bipolar parents (BO; n = 43; 21 females; 11.0 ± 3.2 years) and controls (n = 42; 17 females; 11.1 ± 3.4 years) comparable in sex (p = .4) and age (p = .7). All participants wore a MotionWatch 8 (Camntech, Cambridge, UK) actigraph on their nondominant wrist for ≥ 14 days and completed sleep diaries. Psychopathology was assessed by the Kiddie Schedule for Affective Disorders and Schizophrenia and by subjective scales. The main areas of interest were rest-activity circadian rhythmicity, chronotype and sleep macrostructure. Subgroup analyses (child and adolescent subgroups) were conducted to identify physiological differences in sleep between these age groups. The BO and controls did not differ in the presence of current mood (p = .5) and anxiety (p = .6) disorders. The BO had shorter sleep time on free days (p = .007; effect size, Cohen´s d = 0.56), lower sleep efficiency on free days (p = .01; d = 0.47), lower prolongation of time in bed on free days (p = .046; d = 0.41), and lower social jet lag (p = .04; d = 0.5) than the controls. A longer sleep time on school days (p < .001; d = 0.21), lower prolongation of sleep time between school and free days (p = .008; d = 0.74), and larger difference in sleep onset latency between school days and free days (p = .009; d = 0.52) were observed in the adolescent BO than in the controls. The child BO had poorer sleep quality on free days than the controls (p = .02; d = 0.96). In all cases, the results remained significant after controlling for subthreshold mood and anxiety symptoms. The BO had less variable rest-activity rhythm than controls (p = .04; d = 0.32). No other significant differences between the BO and controls were observed in the rest-activity circadian rhythmicity and chronotype. The results showed decreased physiological catch-up sleep on free days in the BO, which may indicate a decreased need for sleep in this population. Thus, the decreased need for sleep observed in the unaffected BO may represent an endophenotype of BD.

No wink of sleep: Population sleep characteristics in response to the brexit poll and the 2016 U.S. presidential election.

INTRODUCTION: Personal well-being, including people's sleep characteristics, is affected by a variety of factors, one example of which is wide-ranging high-impact public events. In this study, we use a large sleep database obtained through a smartphone application for sleep tracking via anonymized time-sampled data to study the effect of two political events with a wide-ranging impact on people's sleep characteristics: the Brexit referendum in June 2016, and the presidential election of Donald Trump in November 2016 METHOD: Using Sleep as Android - an actigraphy-based sleep monitoring smartphone application - we collected 10.5 million geo-located sleep records from more than 69,000 users in Europe and North America. Population-based changes in sleep around each of these two events, in the United Kingdom and in the United States of America, were assessed using a non-parametric bootstrap test RESULTS: The analysis revealed a significant reduction by 16 min and 21 s in the mean sleep duration of British people in the night after the Brexit poll (p < 0.001). Similarly, the analysis of the US presidential election revealed a significant 12 min 49 s drop in the mean sleep duration during the night following the event, in comparison with the whole studied region (p < 0.001), and an increase by 5 min and 9 s in the subsequent night (p = 0.0328). Additional analysis comparing the election night to comparable days in preceding years revealed that the actual reduction in sleep length may have been even greater. There is also an increase in the proportion of subjects with very short sleep CONCLUSIONS: The results demonstrate a significant impact of two specific major political events on population sleep characteristics. Our results further underline the potential of mobile applications and informatics approaches in general to provide data that enable us to investigate fundamental physiological variables over time and location.