Tendency toward eveningness is associated with unhealthy dietary habits

Subjects with higher preference for evening hours in daily activities (eveningness) have been repeatedly shown to practice adverse health behaviors as compared to those preferring morning hours (morningness). However, associations between chronotype and dietary intake have not been explored intensively. The authors explored whether the human chronotype is associated with food and nutrient intakes in a random sample of the population aged 25 to 74 yrs. The cross-sectional study included 4493 subjects from the National FINRISK 2007 Study. Chronotype was assessed using a shortened version of Horne and ?stberg's Morningness-Eveningness Questionnaire. Diet was assessed using a validated food frequency questionnaire. Associations between morningness-eveningness (ME) score and dietary intakes were analyzed by linear regression and difference between lowest (eveningness) and highest (morningness) ME score quintiles by Tukey's test. In the multivariable model, intakes of whole grain, rye, potatoes, and vegetables and roots decreased, whereas those of wine and chocolate increased with lower ME scores. Participants in the lowest ME score quintile consumed less fish (p 相似文献   

Morningness: Protective Factor for Sleep-Related and Emotional Problems in Childhood and Adolescence?

The relationship between morningness/eveningness, sleep, and psychological problems is well documented in adults as well as in adolescents. However, research on the circadian orientation and its concomitants in younger children is scarce. The authors investigated the distribution of morningness/eveningness and its connection to sleeping and psychological problems in 91 children and 151 adolescents in Austria. The authors found that morning (M) types had less sleep-related and psychological problems than intermediate (I) and evening (E) types, respectively. Among children, M-types suffered less from daytime sleepiness (females: χ²₍₂₎?=?8.1, p?=?.017; males: χ²₍₂₎?=?14.8, p?=?.001). Among adolescents, M-types showed fewer sleep-wake problems (females: χ²₍₂₎?=?17.5, p?<?.001; males: χ²₍₂₎?=?19.8, p?<?.001), and female M-types showed less externalizing (χ²₍₂₎?=?8.7, p?=?.013) as well as internalizing problem behavior (χ²₍₂₎?=?9.0, p?=?.011). In conclusion, these findings indicate that morningness may act as a protective factor against the development of sleep-related problems in childhood and sleep-related and psychological problems in adolescence, especially in females. (Author correspondence: gloriagelbmann@gmx.at)     

Chronotype and its relationship with sleep disorders in children with attention deficit hyperactivity disorder

Chronotype can be classified as morningness types, people who prefer morning hours for their physical and mental activities; eveningness types, people who prefer the afternoon or evening hours; and intermediate types, those who show characteristics of both morningness and eveningness types. Attention deficit hyperactivity disorder (ADHD) has been linked with disturbances in chronotype, particularly increased eveningness. Despite the possibility of an association between chronotypes, sleep disturbances and ADHD symptoms, there is little evidence of this association considering the child population. The purpose of this study was to examine chronotype preferences in children aged between 7 and 12 years who were diagnosed as having ADHD in the context of sleep disturbances. The Schedule for Affective Disorders and Schizophrenia for School Age Children-Present and Lifetime Version, Conner’s Rating Scales, Children’s Sleep Habit Questionnaire and Children’s Chronotype Questionnaire were used for the evaluation of children with ADHD and healthy controls. The ADHD group was 73% combined-type, and the eveningness scores of the ADHD group (n = 52) were significantly higher than the control group (n = 52) (p < 0.01). There was a positive correlation between the higher scores of eveningness and total scores on resistance to sleep time (p < 0.09), respiratory problems during sleep and daytime sleepiness in the ADHD group. CSHQ total score was found to be a predictive factor for eveningness among children with ADHD (p < 0.01). These findings highlight possible reciprocal links between ADHD symptoms, sleep disturbances and chronotype in children aged 7–12 years, which might lead to individualized treatment options.     

EPIGENETIC EFFECTS OF SHIFTWORK ON BLOOD DNA METHYLATION

In the present study, the authors investigated the effects of shiftwork exposure on DNA methylation using peripheral blood DNA from subjects working in two chemical plants in Northern Italy. The investigation was designed to evaluate (a) DNA methylation changes in Alu and long interspersed nuclear element-1 (LINE-1) repetitive elements as a surrogate of global methylation and (b) promoter methylation of glucocorticoid receptor (GCR), tumor necrosis factor alpha (TNF-α), and interferon-gamma (IFN-γ). One hundred and fifty white male workers (mean?±?SD: 41.0?±?9 yrs of age) were examined: 100 3?×?8 rotating shiftworkers (40.4?±?8.7 yrs of age) and 50 day workers (42.2?±?9.4 yrs of age). The authors used bisulfite-pyrosequencing to estimate repetitive elements and gene-specific methylation. Multiple regression analysis, adjusted for age, body mass index (BMI), and job seniority, did not show any significant association between the five DNA methylation markers and shiftwork. However, job seniority, in all subjects, was significantly associated with Alu (β?=??0.019, p?=?.033) and IFN-γ (β?=??0.224, p?<?.001) methylation, whereas TNF-α methylation was inversely correlated with age (β?=??0.093, p?<?.001). Considering only shiftworkers, multiple regression analysis, adjusted for age, BMI, and job seniority, showed a significant difference between morning and evening types in TNF-α methylation (mean morning type [MT] 11.425 %5mC versus evening type [ET] 12.975 %5mC; β?=?1.33, p?=?.022). No difference was observed between good and poor tolerance to shiftwork. Increasing job seniority (<5, 5–15, >15 yrs) was associated with significantly lower Alu (β?=??0.86, p?=?.006) and IFN-γ methylation (β?=??6.50, p?=?.007) after adjustment for age, BMI, and morningness/eveningness. In addition, GCR significantly increased with length of shiftwork (β?=?3.33, p?=?.05). The data showed alterations in blood DNA methylation in a group of shiftworkers, including changes in Alu repetitive elements methylation and gene-specific methylation of IFN-γ and TNF-α promoters. Further studies are required to determine the role of such alterations in mediating the effects of shiftwork on human health. (Author correspondence: giovanni.costa@unimi.it)     

Light Exposure Among Adolescents With Delayed Sleep Phase Disorder: A Prospective Cohort Study

The objective of this study was to compare light exposure and sleep parameters between adolescents with delayed sleep phase disorder (DSPD; n?=?16, 15.3?±?1.8 yrs) and unaffected controls (n?=?22, 13.7?±?2.4 yrs) using a prospective cohort design. Participants wore wrist actigraphs with photosensors for 14 days. Mean hourly lux levels from 20:00 to 05:00?h and 05:00 to 14:00?h were examined, in addition to the 9-h intervals prior to sleep onset and after sleep offset. Sleep parameters were compared separately, and were also included as covariates within models that analyzed associations with specified light intervals. Additional covariates included group and school night status. Adolescent delayed sleep phase subjects received more evening (p?<?.02, 22:00–02:00?h) and less morning (p?<?.05, 08:00–09:00?h and 10:00–12:00?h) light than controls, but had less pre-sleep exposure with adjustments for the time of sleep onset (p?<?.03, 5–7?h prior to onset hour). No differences were identified with respect to the sleep offset interval. Increased total sleep time and later sleep offset times were associated with decreased evening (p?<?.001 and p?=?.02, respectively) and morning (p?=?.01 and p?<?.001, respectively) light exposure, and later sleep onset times were associated with increased evening exposure (p?<?.001). Increased total sleep time also correlated with increased exposure during the 9?h before sleep onset (p?=?.01), and a later sleep onset time corresponded with decreased light exposure during the same interval (p?<?.001). Outcomes persisted regardless of school night status. In conclusion, light exposure interpretation requires adjustments for sleep timing among adolescents with DSPD. Pre- and post-sleep light exposures do not appear to contribute directly to phase delays. Sensitivity to morning light may be reduced among adolescents with DSPD. (Author correspondence: auger.raymond1@mayo.edu)     

The associations between chronotype,a healthy diet and obesity

Unhealthy diet has been associated with obesity. Evening type has been associated with unhealthier food and nutrient intake that could predict a higher risk of obesity among them as compared to morning type. However, thus far no study has examined the interrelationships between chronotype, a healthy diet and obesity. We examined whether a healthy diet mediates the association between chronotype and obesity and whether chronotype modifies the association between a healthy and obesity. The National FINRISK 2007 Study included 4421 subjects aged 25–74 years. Diet was assessed using a validated food frequency questionnaire. Baltic Sea diet score (BSDS), including nine dietary components, was used as a measure of adherence to a healthy Nordic diet. Weight, height, body fat percentage and waist circumference were measured, and body mass index values were calculated. Chronotype was assessed using a shortened version of Horne and Östberg’s morningness–eveningness questionnaire (MEQ). The sum score calculated from MEQ was either used as a continuous variable or divided into tertiles of which the lowest tertile demonstrated evening preference and the highest tertile demonstrated morning preference. A series of regression analyses were conducted to determine whether the BSDS mediates the association between chronotype and obesity. Likelihood ratio test was used to determine whether chronotype modifies the association between the BSDS and the obesity measures. After testing the interaction, chronotype-stratified analysis for the association between the BSDS and obesity measures was determined by linear regression. Generally, the evening types had lower adherence to the BSDS and were more often smokers (men), physically inactive and had lower perceived health than the other chronotypes (p < 0.05). The poorer health behavior of this group, however, was not manifested in their obesity measures, and no evidence that the BSDS would mediate the association between chronotype and obesity was found (p > 0.05). No evidence that chronotype would modify the association between the BSDS and obesity was found either (p > 0.05).     

Relevance of chronotype for eating patterns in adolescents

During adolescence, a shift from morningness to eveningness occurs, yet school continues to start early in the morning. Hence, adolescents are at risk for social jetlag, i.e. a discrepancy between biological and social timing. It remains to be determined whether chronotype associates with daily and daytime-specific eating patterns during this potentially critical period. Therefore, the aim of the present study was to investigate whether chronotype is decisive for daily eating patterns [total energy intake (TEI, kcal), total macronutrient intake (% of TEI), eating occasion frequency (n/day), meal frequency (n/day), snack frequency (n/day), duration of nightly fasting], or daytime-specific eating patterns [morning (before 11 am) energy intake (% of TEI), morning macronutrient intake (% of morning energy intake), regular breakfast skipping (no morning energy intake at least on 2 of 3?days, yes/no), evening (after 6 pm) energy intake (% of TEI), evening macronutrient intake (% of evening energy intake), regular dinner skipping (no evening energy intake at least on 2 of 3?days, yes/no)] in German adolescents. Chronotype was assessed by use of the Munich Chronotype Questionnaire and is defined as the midpoint of sleep corrected for sleep-debt accumulated over the workweek (the later the midpoint of sleep, the later the chronotype). A total of 223 participants (10–18?years) provided 346 questionnaires and concurrent 3-day weighed dietary records. Associations between chronotype and eating patterns were analyzed cross-sectionally using multivariable linear and logistic mixed-effects regression models. Adolescents with earlier and later chronotypes did not differ in their daily eating patterns. With respect to daytime-specific eating patterns, 1?h delay in chronotype was associated with 4.0 (95% CI 2.5–6.6) greater odds of regular breakfast skipping (p < 0.0001). In addition, later chronotype was associated with higher evening energy intake (p = 0.0009). In conclusion, our data show that a later chronotype among adolescents is associated with a shift of food consumption toward later times of the day. Hence, adolescents’ eating patterns appear to follow their internal clock rather than socially determined schedules.     

CHRONOTYPES AND SUBJECTIVE SLEEP PARAMETERS IN EPILEPSY PATIENTS: A LARGE QUESTIONNAIRE STUDY

Accumulating evidence suggests epilepsy and seizures may influence circadian rhythms and that circadian rhythms may influence epilepsy. It is also conceivable that seizure timing influences the timing of daily activities, sleeping, and wakefulness (i.e., chronotype). Only one group has studied the distribution of chronotypes of epileptics, showing significant differences between the diurnal activity patterns in two groups of patients with different epilepsy syndromes. The authors performed a questionnaire-based study of 200 epilepsy patients to compare the distribution of chronotypes and subjective sleep parameters of sleep duration and time of mid-sleep on free days to the distribution in the general population (n?=?4042). Within this large group of epilepsy patients, we also compared the chronotypes of subsamples with well-defined epilepsy syndromes, i.e., temporal lobe epilepsy [TLE; n?=?46], frontal lobe epilepsy [FLE; n?=?30], and juvenile myoclonic epilepsy [JME; n?=?38]. In addition, 27 patients who had had surgery for TLE were compared with those with TLE who had not had surgery. Both the Morningness-Eveningness Questionnaire and Munich Chronotype Questionnaire were used to determine chronotypes and subjective sleep parameters. Significant differences in morningness/eveningness distribution, timing of mid-sleep (corrected for sleep duration), and total sleep time on free days were found between epileptics and healthy controls. Those with epilepsy were more morning oriented, had earlier mid-sleep on free days, and longer sleep duration on free days (p?<?.001). However, distributions of chronotypes and sleep parameters between the groups of people with TLE, FLE, and JME did not differ. Persons who had surgery for TLE had similar morningness-eveningness parameters and similar sleep durations compared to those without surgery, but mid-sleep on free days was earlier in operated patients (p?=?.039). In conclusion, this is the first large study focusing on chronotypes in people with epilepsy. We show that the distribution of chronotypes and subjective sleep parameters of epileptics, in general, is different from that of healthy controls. Nevertheless, no differences are observed between patients with specified epilepsy syndromes, although they exhibit seizures with different diurnal patterns. Our results suggest that epilepsy, itself, rather than seizure timing, has a significant influence on chronotype behavior and subjective sleep parameters. (Author correspondence: w.hofstra@mst.nl)     

Eveningness as a risk for behavioral problems in late adolescence

Circadian preference toward eveningness has been associated with increased risk for mental health problems both in early adolescence and in adulthood. However, in late adolescence, when circadian rhythm naturally shifts to later, its significance for mental health is not clear. Accordingly, we studied how circadian rhythm estimated both by self-reported chronotype and by actigraph-defined midpoint of sleep was associated with self-reported psychiatric problems based on Youth Self Report (YSR). The study builds on a community cohort born in 1998, Helsinki, Finland. At age 17 years (mean age = 16.9, SD = 0.1 years), 183 adolescents (65.6% of the invited) participated in the study. We used the shortened version of the Horne-Östberg morningness–eveningness Questionnaire to define the chronotype, and actigraphs to define the naturally occur circadian rhythm over a 4 to 17 days’ period (mean nights N = 8.3, SD = 1.8). The Achenbach software was used to obtain T-score values for YSR psychiatric problem scales. The analyses were adjusted for important covariates including gender, socioeconomic status, body mass index, pubertal maturation, mother’s licorice consumption during pregnancy, and actigraph-defined sleep duration and quality. Eveningness was associated with higher scores in rule-breaking behavior and conduct problems (as assessed either by midpoint of sleep or by self-reported chronotype, p-values <0.05), attention deficit/hyperactivity problems (by self-reported chronotype, p-values <0.05), with affective problems (by midpoint of sleep and by self-reported chronotype, p-values <0.05) and somatic complaints (by self-reported chronotype, p-values <0.05), as compared to circadian tendency toward morningness. Our results suggest that the association between eveningness and externalizing problem behavior, present in children and younger adolescents, is also present in late adolescence when circadian rhythms shift toward evening.     

Association Study of a Variable-Number Tandem Repeat Polymorphism in the Clock Gene PERIOD3 and Chronotype in Norwegian University Students

Circadian rhythms are endogenously generated cycles involving physiological parameters, such as core body temperature, hormone levels, blood pressure, sleep, and metabolism, with a period length of around 24?h. The circadian clock in mammals is regulated by a set of clock genes that are functionally linked together, and polymorphisms in clock genes could be associated with differences in circadian rhythms. A variable-number tandem repeat (VNTR) in the human clock gene PERIOD3 (PER3) has been suggested to correlate with a morning (lark) versus evening (owl) chronotype as well as with the circadian rhythm sleep disorder “delayed sleep phase disorder” (DSPD). The authors examined 432 healthy Norwegian university students in search of further support for an association between the PER3 polymorphism and diurnal preference. The Horne-Östberg Morningness-Eveningness Questionnaire (MEQ) and Preferences Scale (PS) were used to evaluate subjective chronotype. DNA samples were genotyped with respect to the 4-repeat and 5-repeat alleles of the VNTR PER3 polymorphism, and the genotype distribution was 192 (4-4), 191 (4-5), and 49 (5-5). The authors estimated that the power to detect an association of the 4-allele with preference for morningness or eveningness was 75%. The authors found no association between the PER3 clock gene and chronotype, indicating that the proposed role of PER3 needs further clarification. (Author correspondence: teresa.osland@med.uib.no)     

Morningness/Eveningness and Satisfaction With Life in a Polish Sample

Previous studies have provided evidence that eveningness could be related to disadvantageous individual characteristics. The hypothesis that more evening-oriented individuals exhibit lower satisfaction with life has been tested by Randler using a sample of 164 German university students, and this showed that eveningness is associated with lower satisfaction with life (r?=?.177). The aim of the present study was to answer the question of whether or not this relationship is culturally independent, and would exist if a sample from another geographical location and culture had been studied. A sample of 349 residents (149 men) aged between 13 and 59 yrs from two Polish cities completed the Morningness-Eveningness Questionnaire and the Satisfaction with Life Scale. Analysis revealed that morningness was related to greater life satisfaction (r?=?.105), regardless of age and sex. The magnitude of this relationship did not differ significantly between the Polish and the German sample, which suggests that the magnitude and direction of association between morningness/eveningness and satisfaction with life could be independent of culture or geographical location. (Author correspondence: E-mail: konrad.jankowski@psych.uw.edu.pl)     

Chronotype preferences of college students from varied altitude backgrounds in Ethiopia

ABSTRACT

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.     

Chronotype Differences in Suicidal Behavior and Impulsivity Among Suicide Attempters

Morning- and evening-type individuals differ on a number of psychological and biological variables. There has been increasing interest in the relationship between chronotype and personality traits. The aim of this study was to investigate the relationship between impulsivity and chronotype in suicide attempters. Eighty-nine suicide attempters were included in the study, and systematic information on suicide attempts was recorded. The Morningness-Eveningness Questionnaire was applied to determine chronotype, and attempter impulsivity was measured by the total score of the Barratt Impulsiveness Scale. Significant differences between chronotype and impulsivity scores were found. Evening-type subjects reported significantly higher impulsivity scores than both neither- and morning-types. A significant association between chronotype and type of suicide attempt was detected. The largest proportion of violent suicide attempters were evening-type subjects. Violent suicide attempters also reported significantly higher impulsivity scores than nonviolent attempters. Previous studies have pointed out possible relations between eveningness and impulsivity. Current findings suggest that eveningness may be a risk factor for violent suicide attempts by increasing impulsivity. (Author correspondence: dryavuzselvi@yahoo.com)     

Adipokine Levels Are Altered by Shiftwork: A Preliminary Study

Shiftwork is often associated with metabolic diseases, and in the past few years, several cytokines have been postulated to contribute to various diseases, including insulin resistance. The aim of this study was to compare the concentrations of adiponectin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in samples of young adult men exposed to a fixed (i) night shift (n?=?9), working from 22:00 to 06:00?h; (ii) early morning shift (n?=?6), working from 06:00 to 14:00?h; and (iii) day shift (n?=?7), working from 08:00 to 17:00?h. The fixed night-shift and early-morning-shift samples were considered collectively as a shiftworker group given their work times. Blood samples were collected during the regular working day at 4-h intervals over the course of 24?h, thus totaling six samples. Morphological and physical activity parameters did not differ between the three groups. Total energy intake was lowest on the early morning shifts (p?<?.03). Both shiftworker groups ingested a significantly higher percentage of fat (p?<?.003) and a lower percentage of carbohydrate (p?<?.0005) than the day group. The early morning group had a lower mean 24-h level of adiponectin than the other two groups (p?=?.016), and both the early morning and night groups exhibited higher mean 24-h levels of TNF-α than the day group (p?=?.0001). The 24-h mean levels of IL-6 did not differ significantly between the groups (p?=?.147). None of the groups exhibited a significant circadian effect on adiponectin (p?=?.829), TNF-α (p?=?.779), or IL-6 (p?=?.979) levels. These results indicate that individuals who are enrolled in shiftwork are susceptible to alterations in the secretion of cytokines that are involved in insulin resistance and cardiovascular disease, both of which are known to affect this population. (Author correspondence: tmello@demello.net.br)     

Association of habitual dietary intake with morningness-eveningness and rotating shift work in Japanese female nurses

Rotating shift workers are associated with imbalanced dietary intakes. Rotating shift workers and dietary intakes in adults who do not engage in night work have also been shown to be associated with chronotype. However, no studies have examined associations between morningness-eveningness (i.e., the degree to which people prefer to be active in the morning or the evening), rotating shift work and dietary intakes. Therefore, our first purpose was to elucidate the association between morningness-eveningness and habitual food group intakes in rotating shift workers. The second purpose was to elucidate the association of morningness-eveningness and rotating shift work with food group intakes, considering habitual sleep durations. Japanese nurses (1095 day workers and 1464 rotating shift workers) were studied using a self-administered questionnaire. The questionnaire covered habitual dietary intakes, morningness-eveningness and demographic characteristics of the participants. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure self-rated morningness-eveningness. Dietary intakes over the previous 1 month were evaluated using a semi-quantitative food frequency questionnaire. Intakes of pulses, green/yellow vegetables, white vegetables, fruits, algae, eggs, confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) associated with the MEQ score in rotating shift workers. Among these food groups, intakes of green/yellow vegetables, white vegetables, fruits and algae were significantly (p < 0.05) lower in rotating shift workers than in day workers, and intakes of confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) higher in rotating shift workers than in day workers. Intakes of these food groups were also significantly (p < 0.05) associated with the MEQ score in day workers. In addition, the MEQ score was significantly (p < 0.05) lower in rotating shift workers than in day workers, indicating greater eveningness among rotating shift workers. Multivariate linear regression revealed that the MEQ scores were significantly (p < 0.05) associated with intakes of these food groups, while rotating shift work was associated only with confectioneries/savory snacks. These results suggest that morningness-eveningness is associated with unbalanced dietary intakes in rotating shift workers as well as day workers, which may partially explain associations between rotating shift work and unfavorable dietary intakes. These findings have important implications for the development of novel strategies for preventing poor health caused by imbalanced dietary intakes in rotating shift workers.     

Expression of Clock Genes in Human Subcutaneous and Visceral Adipose Tissues

Disrupted circadian rhythms are associated with obesity and metabolic alterations, but little is known about the participation of peripheral circadian clock machinery in these processes. The aim of the present study was to analyze RNA expression of clock genes in subcutaneous (SAT) and visceral (VAT) adipose tissues of male and female subjects in AM (morning) and PM (afternoon) periods, and its interactions with body mass index (BMI). Ninety-one subjects (41?±?11 yrs of age) presenting a wide range of BMI (21.4 to 48.6?kg/m²) were included. SAT and VAT biopsies were obtained from patients undergoing abdominal surgeries. Clock genes expressions were evaluated by qRT-PCR. The only clock gene that showed higher expression (p?<?.0001) in SAT in comparison to VAT was PER1 of female (372%) and male (326%) subjects. Different patterns of expression between the AM and PM periods were observed, in particular REV-ERBα, which was reduced (p?<?.05) at the PM period in SAT and VAT of both women and men (women: ～53% lower; men: ～78% lower), whereas CLOCK expression was not altered. Relationships between clock genes were different in SAT vs. VAT. BMI was negatively correlated with SATPER1 (r?=??.549; p?=?.001) and SATPER2 (r?=??.613; p?=?.0001) and positively with VATCLOCK (r?=?.541; p?=?.001) and VATBMAL1 (r?=?.468; p?=?.007) only in women. These data suggest that the circadian clock machinery of adipose tissue depots differs between female and male subjects, with a sex-specific effect observed for some genes. BMI correlated with clock genes, but at this moment it is not possible to establish the cause-effect relationship. (Author correspondence: mzanquetta@gmail.com)     

Influence of Chronotype,Season, and Sex of Subject on Sleep Behavior of Young Adults

The aim of this study was to investigate whether sex, season, and/or chronotype influence the sleep behavior of university students. Detailed data were collected on activity/rest patterns by wrist actigraphy combined with diaries. Thirty‐four medical students (19 female and 15 male) were monitored by Actiwatch® actometers for 15 consecutive days in May and again in November. The data of a modified Horne and Östberg chronotype questionnaire, which were collected from 1573 female and 1124 male medical school students surveyed in the spring and autumn over an eight‐year period, were evaluated. Actiwatch® sleep analysis software was used to process the activity data with statistical analyses performed with ANOVA. We found no significant sex‐specific differences in sleep efficiency, sleep onset latency, or actual sleep‐time duration. However, we did find a difference in sleep efficiency between morning and evening types, with morning types having a higher sleep efficiency (87.9%, SD=1.3) than evening types (84.3%, SD=0.87%; p=0.007). Seasonal differences were also detected: the actual sleep‐time duration in autumn was significantly longer (mean 6.9 h, SD=0.13 h) than in spring (6.6 h, SD=0.1 h; p=0.013). Evaluation of the chronotype questionnaire data showed that individuals with no special preference for morningness or eveningness (i.e., so‐called intermediates) were most common. The distribution of chronotypes was related to the sex of subject. Men displayed eveningness significantly more often than women (28.9% males vs. 20.8% females; p<0.001), while females exhibited greater morningness (20.3% females vs.15.6% males; p<0.001). Sex influences chronotype distribution, but not actual sleep time‐duration, sleep onset latency, or sleep efficiency. The latter, however, differed among chronotypes, while actual sleep‐time duration was affected by season.     

Associations of common noncommunicable medical conditions and chronic diseases with chronotype in a population-based health examination study

Chronotype is an emerging predictor of health and longevity, and understanding its influence on chronic diseases is important for constructing conceptual models of long-term pathways to health. We assessed the associations of chronotype with health status in the general Finnish adult population. Our population-based data were derived from the National FINRISK 2012 study and consisted of 4414 participants, aged 25–74?years, living in Finland. As part of their health examination, participants were asked about their circadian preference to the daily activities (morningness–eveningness) and a diagnosis or treatment for a set of common noncommunicable medical conditions and chronic diseases during the past 12?months. We found that there were 1935 (43.8%) morning types (MTs) and 595 (13.5%) evening types (ETs) and that 1884 (42.7%) were intermediates. As compared with the MTs, the ETs had significantly greater odds for depression (OR = 2.44, 95% CI = 1.52–3.90, p < 0.001) and other mental disorders (OR = 5.18, 95% CI = 2.32–11.52, p < 0.001). The odds were also increased for gallstones, and chronic obstructive pulmonary disease, but these did not remain significant after controlling for multiple testing. Responses to the single-item subjective estimation on the chronotype yielded the association of the definitely evening type of persons with the diagnosis or treatment of cardiac insufficiency (OR = 1.99, 95% CI = 1.02–3.88, p = 0.044) that was corroborated as the greater the eveningness score was, the more common the diagnosis or treatment of cardiac insufficiency was (β = 0.92, 95% CI = 0.85–0.98, p = 0.013). This exploratory study adds further support to the role of evening chronotype in chronic disease risk, albeit underlying mechanisms remain to be elucidated.     

PARENTAL ENFORCEMENT OF BEDTIME DURING CHILDHOOD MODULATES PREFERENCE OF JAPANESE JUNIOR HIGH SCHOOL STUDENTS FOR EVENINGNESS CHRONOTYPE

We examined the effect of home bedtime discipline during childhood on morningness and eveningness (M-E) preference by Japanese junior high school students. M-E was assessed by the M-E Questionnaire (MEQ) of Torsvall and Åkerstedt (the higher the score, the greater the preference for morningness), and parental determination of bedtime during childhood was ascertained using an original questionnaire. The average M-E score of adolescents living in urban Kochi City (mean ± SD; 15.10 ± 3.42) was significantly lower (P <. 01) than the score of those in suburban districts (16.14 ± 3.44). Overall, 43.1% of the junior high school students in Kochi City compared to 53.0% of the students living in suburban districts had their bedtime decided during childhood by parents (P <. 01). In Kochi City, the M-E score for boys (14.62 ± 3.51) was lower (P <. 01) than girls (15.53 ± 3.28). During childhood, parents decided the bedtime for 49% of the girls compared to 36.6% of the boys (P <. 01). Boys whose bedtime was not decided by parents during childhood had a somewhat stronger preference for eveningness (14.20 ± 3.53) (P <. 05) compared to those whose bedtime was decided by parents (15.12 ± 3.36). The results suggest bedtime discipline at home during childhood has an effect on adolescent chronotype, modulating the extent of shift to eveningness in Japanese junior high school boys in particular. (Chronobiology International, 18(5), 823–829, 2001)     

CHRONIC SLEEP DEFICIT AND PERFORMANCE OF A SUSTAINED ATTENTION TASK—AN ELECTROOCULOGRAPHY STUDY

Electrooculography (EOG) was used to explore performance differences in a sustained attention task during rested wakefulness (RW) and after 7 days of partial sleep deprivation (SD). The RW condition was based on obtaining regular sleep, and the SD condition involved sleep restriction of 3?h/night for a week resulting in a total sleep debt of 21?h. The study used a counterbalanced design with a 2-wk gap between the conditions. Participants performed a sustained attention task for 45?min on four occasions: 10:00–11:00, 14:00–15:00, 18:00–19:00, and 22:00–23:00?h. The task required moving gaze and attention as fast as possible from a fixation point to a target. In each session, 120 congruent and 34 incongruent stimuli were presented, totaling 1232 observations/participant. Correct responses plus errors of omission (lapses) and commission (false responses) were recorded, and the effect of time-of-day on sustained attention following SD was investigated. The analysis of variance (ANOVA) model showed that SD affected performance on a sustained attention task and manifested itself in a higher number of omission errors: congruent stimuli (F_(1,64)?=?13.3, p?<?.001) and incongruent stimuli (F_(1,64)?=?14.0, p?<?.001). Reaction times for saccadic eye movements did not differ significantly between experimental conditions or by time-of-day. Commission errors, however, exhibited a decreasing trend during the day. The visible prevalence of omissions in SD versus RW was observed during the mid-afternoon hours (the so-called post-lunch dip) for both congruent and incongruent stimuli (F_(1,16)?=?5.3, p?=?.04 and F_(1,16)?=?5.6, p?=?.03, respectively), and at 18:00?h for incongruent stimuli (F_(1,13)?=?5.7, p?=?.03). (Author correspondence: magda.fafrowicz@uj.edu.pl)