Chronotype and time-of-day influences on the alerting,orienting, and executive components of attention

Recent research on attention has identified three separable components, known as alerting, orienting, and executive functioning, which are thought to be subserved by distinct neural networks. Despite systematic investigation into their relatedness to each other and to psychopathology, little is known about how these three networks might be modulated by such factors as time-of-day and chronotype. The present study administered the Attentional Network Test (ANT) and a self-report measure of alertness to 80 participants at 0800, 1200, 1600, and 2000 hours on the same day. Participants were also chronotyped with a morningness/eveningness questionnaire and divided into evening versus morning/neither-type groups; morning chronotypes tend to perform better early in the day, while evening chronotypes show enhanced performance later in the day. The results replicated the lack of any correlations between alerting, orienting, and executive functioning, supporting the independence of these three networks. There was an effect of time-of-day on executive functioning with higher conflict scores at 1200 and 1600 hours for both chronotypes. The efficiency of the orienting system did not change as a function of time-of-day or chronotype. The alerting measure, however, showed an interaction between time-of-day and chronotype such that alerting scores increased only for the morning/neither-type participants in the latter half of the day. There was also an interaction between time-of-day and chronotype for self-reported alertness, such that it increased during the first half of the day for all participants, but then decreased for morning/neither types (only) toward evening. This is the first report to examine changes in the trinity of attentional networks measured by the ANT throughout a normal day in a large group of normal participants, and it encourages more integration between chronobiology and cognitive neuroscience for both theoretical and practical reasons. An erratum to this article can be found at     

Chronotype,social jet lag,sleep debt and food timing in inflammatory bowel disease

The preference of the sleep/wake cycle can be grouped into categories or chronotypes. Inflammatory bowel disease (IBD) has been linked to poor sleep quality which correlates with disease severity. Social jet lag (SJL) is the difference between sleep timing on work and free days and is a marker for circadian misalignment which has been linked to increased inflammation. We investigated whether chronotype, SJL, sleep debt (SD), and food timing were associated with an IBD specific complications and a lower quality of life. Overall, 191 subjects (115 IBD subjects and 76 healthy controls (HC)) completed the Pittsburgh Sleep Quality Index (PSQI), Morningness-Eveningness Questionnaire (MEQ), Munich ChronoType Questionnaire (MCTQ), Short Inflammatory Bowel Disease Questionnaire (SIBDQ), and a structured Food Timing Questionnaire. Later chronotype (by MEQ) was associated with a worse SIBDQ (r = −0.209; P < 0.05). SJL was increased in IBD at 1.32 h ± 1.03 vs. 1.05 h ± 0.97 in HC, P < 0.05, when adjusted for age. SJL (>2 h) was present in 40% of severe/complicated Crohn's patients (fistulizing or structuring Crohn's or history of Crohn's related surgery) compared to only 16% of uncomplicated Crohn's patients (P < 0.05). Sleep debt was increased in IBD subjects compared to HC at 21.90 m ± 25.37 vs. 11.49 m ± 13.58, P < 0.05. IBD subjects with inconsistent breakfast or dinner times had lower SIBDQ scores (4.78 ± 1.28 vs. 5.49 ± 1.02, P < 0.05; 4.95 ± 0.31 vs. 5.42 ± 0.32, P < 0.05 respectively). In summary, later chronotype, and markers of circadian misalignment (social jet lag, sleep debt, and inconsistent meal timing) were associated with IBD disease specific complications and/or lower quality of life.     

A time to think: Circadian rhythms in human cognition

Although peaks and troughs in cognitive performance characterize our daily functioning, time-of-day fluctuations remain marginally considered in the domain of cognitive psychology and neuropsychology. Here, we attempt to summarize studies looking at the effects of sleep pressure, circadian variations, and chronotype on cognitive functioning in healthy subjects. The picture that emerges from this assessment is that beyond physiological variables, time-of-day modulations affect performance on a wide range of cognitive tasks measuring attentional capacities, executive functioning, and memory. These performance fluctuations are also contingent upon the chronotype, which reflects interindividual differences in circadian preference, and particularly upon the synchronicity between the individuals' peak periods of circadian arousal and the time of the day at which testing occurs. In themselves, these conclusions should direct both the clinician's and the researcher's attention towards the utmost importance to account for time-of-day parameters when assessing cognitive performance in patients and healthy volunteers.     

Evaluation of Two Circadian Rhythm Questionnaires for Screening for the Delayed Sleep Phase Disorder

Objective

Delayed sleep phase disorder (DSPD) is a condition in which patients often fall asleep some hours after midnight and have difficulty waking up in the morning. Circadian chronotype questionnaires such as Horne-Östberg Morningness-Eveningness Questionnaire (MEQ) and Basic Language Morningness (BALM) scale have been used for screening for DSPD. This study was to evaluate these two chronotype questionnaires for screening of DSPD.

Methods

The study samples were 444 DSPD and 438 controls. Cronbach''s alpha coefficient was calculated to evaluate for internal consistency. An exploratory factor analysis was conducted using principal-axis factoring. The diagnostic performance of a test was evaluated using Receiver Operating Characteristic (ROC) curve analysis. A discriminant function analysis was also performed.

Results

For internal consistency, Cronbach''s alpha of 0.898 for BALM was higher than the 0.837 for MEQ, though both have acceptable internal consistency. BALM has better construct validity than the MEQ because some MEQ items measure different dimensions. However, when we evaluated the efficiency of two questionnaires for DSPD diagnosis by using the ROC curve, the BALM was similar to the MEQ. In a discriminant analysis with the BALM to classify the two groups (DSPD vs. normal), 6 items were identified that resulted in good classification accuracy. Upon examination of the classification procedure, 94.2% of the originally grouped cases were classified correctly.

Conclusion

These findings suggest that the BALM has better psychometric properties than the MEQ in screening and discriminating DSPS.     

Age and gender variations of sleep in subjects without sleep disorders

Objective. Although sleep is a biomarker for general health and pathological conditions, its changes across age and gender are poorly understood.

Methods. Subjective evaluation of sleep was assessed by questionnaires in 5,064 subjects, and 2,966 were considered without sleep disorders. Objective evaluation was performed by polysomnography in 2,160 subjects, and 1,147 were considered without sleep disorders. Only subjects without sleep disorders were included (aged 40–80 years).

Results. Aging was strongly associated with morning preference. Older subjects, especially women, complained less about sleepiness, and pathological sleepiness was significantly lower than in younger subjects. Self-reported sleep quality and daytime functioning improved with aging. Sleep latency increased with age in women, while sleep efficiency decreased with age in both genders. Deep slow-wave sleep decreased with age, but men were more affected. Spectral power densities within slow waves (< 5 Hz) and fast spindles (14–14.75 Hz) decreased, while theta-alpha (5-1 Hz) and beta (16.75–25 Hz) power in non-rapid eye movement sleep increased with aging. In REM sleep, aging was associated with a progressive decrease in delta (1.25–4.5 Hz) and increase in higher frequencies.

Conclusions. Our findings indicate that sleep complaints should not be viewed as part of normal aging but should prompt the identification of underlying causes.     

Chronotype but not sleep length is related to salivary testosterone in young adult men

Sex hormones, including testosterone, are hypothesized to have an influence on the human circadian system. We sampled male students in the period after adolescence. We used the Composite Scale of Morningness (CSM) to assess chronotype and saliva testosterone sampling in 106 University students (23.87±3.56 years; range 19-37) between 26.4.2011 and 6.5.2011, always between 0800h and 0900h. There was a significant negative relationship between CSM scores and saliva testosterone (r(s)=-0.220, p=0.023, two-tailed test) but not between testosterone and average sleep length. Age and testosterone did not correlate with each other nor did age and CSM scores. Our data suggest that chronotype in men might be influenced by testosterone and that high testosterone levels lead to a stronger evening-orientation. Sleep duration was uncorrelated with testosterone, suggesting that timing of sleep - rather than sleep length itself - is influenced by testosterone.     

Genetic variants for morningness in relation to habitual sleep-wake behavior and diurnal preference in a population-based sample of 17,243 adults

ObjectiveAssociations of eveningness with health hazards benefit from analyzing to what extent the polygenic score for morningness correlates with the assessments of the behavioral trait of morningness-eveningness and chronotype.MethodsWith a population-based sample of 17,243 Finnish adults, aged 25–74 years, this study examines the associations of four feasible assessment methods of chronotype, a) biological the genetic liability based on the polygenic score for morningness (PGS_morn), b) the widely-used single item for self-assessed morningness/eveningness (MEQ_i19) of the original Morningness-Eveningness Questionnaire (MEQ), c) the behavioral trait of morningness-eveningness as assessed with the score on the shortened version (sMEQ) of the original MEQ, and d) the phase of entrainment as assessed with the habitual midpoint of sleep based on the self-reported sleep-wake schedule during weekend (Sleep_mid-wknd) as well as the sleep debt corrected midpoint of sleep (Sleep_mid-corr).ResultsAll self-report measures correlated with each other, but very weakly with the PGS_morn, which explained 1–2% of the variation in diurnal preference or habitual sleep-wake schedule. The influence of age was greater on Sleep_mid-wknd and Sleep_mid-corr than on the sMEQ or MEQ_i19, indicating that the diurnal preference might be a more stable indicator for morningness-eveningness than the sleep-wake schedule. Analyses of the discrepancies between sMEQ and MEQ_i19 indicated that eveningness can be over-estimated when relying on only the single-item self-assessment.ConclusionsThe current polygenic score for morningness explains only a small proportion of the variation in diurnal preference or habitual sleep-wake schedule. The molecular genetic basis for morningness-eveningness needs further elucidation.     

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

ObjectiveSleep 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.MethodsA 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.ResultsThe 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.ConclusionEach type of sleep-related problem had its own associated life habit factors.     

The actigraphic documentation of circadian sleep-wake rhythm dysregulation in myotonic dystrophy type 1

Study objectivesThe present study aimed at identifying the sleep-wake rhythm in patients with myotonic dystrophy type 1 (DM1) compared to healthy controls.MethodsPatients with genetic diagnosis of DM1 and healthy controls underwent a 7-day actigraphic recording and filled out a daily sleep diary to evaluate the sleep-wake rhythm. All participants underwent a physical and neurological examination to exclude conditions interfering with the sleep-wake cycle. Daytime activity, nocturnal sleep, and non-parametric circadian rhythm activity (NPCRA) were analysed.ResultsTwenty-nine patients affected by DM1 were included in the present study and were compared to 16 controls. Considering nocturnal actigraphic data, DM1 patients showed a longer time in bed, sleep period time, actual sleep time, and sleep latency compared to controls. Central phase measurement was significantly longer in DM1 patients than controls. At NPCRA analysis patients showed a lower degree of regularity in the activity-rest pattern compared to controls. Moreover, DM1 patients showed reduced motor activity during daytime and a lower synchronization of the rest-activity rhythm than controls.ConclusionsThis study documented that patients with DM1 not only present the impairment of nocturnal sleep, but also show a dysregulation of the sleep-wake circadian rhythm; moreover, reduced amplitude of the circadian rhythmicity was also evident in comparison to controls, probably in relation to the reduced diurnal motor activity of patients. These findings add further evidence to the already documented sleep impairment and excessive daytime sleepiness in DM1 patients.     

Sleep duration rather than sleep timing is associated with obesity in adolescents

ObjectiveIn this study, we investigated differences in sleep patterns between obese and non-obese adolescents, and determined which sleep-related parameters were associated with a risk of adolescent obesity.MethodsIn this cross-sectional study, we evaluated 22,906 adolescents between 12 and 18 years of age (mean 15.2 ± 1.7 years; male 50.9%). Self-report questionnaires were used to assess body mass index (BMI) and sleep habits. Obesity was defined as a BMI-for-age ≥ 95th percentile. Weekend catch-up sleep (CUS) duration was calculated as the sleep duration on free days minus sleep duration on school days. We estimated mid-sleep time on free days corrected for oversleep on free days (MSFsc) and social jet lag. Then, we performed multivariate analysis for adolescent obesity and BMI, respectively.ResultsThe prevalence of obesity was 6.0%. The average sleep duration (P = 0.017) and weekend CUS duration (P < 0.001) of obese adolescents were shorter than those of non-obese adolescents. However, there was no significant difference in MSFsc or social jet lag by the obesity status. After adjustment, obesity was significantly associated with short average sleep duration (odds ratio [OR] 0.91, 95% confidence interval [CI] 0.86–0.96) and short weekend CUS duration (OR 0.92, 95% CI 0.89–0.95). Similarly, BMI was inversely correlated with average sleep duration (B = −0.15, 95% CI -0.19 to −0.11) and weekend CUS duration (B = −0.09, 95% CI -0.11 to −0.06).ConclusionsOur observations suggest that short sleep duration, rather than late MSFsc or social jet lag, was associated with adolescent obesity.