Extreme morning chronotypes are often familial and not exceedingly rare: the estimated prevalence of advanced sleep phase, familial advanced sleep phase, and advanced sleep-wake phase disorder in a sleep clinic population.

Study objectivesReport the first prevalence estimates of advanced sleep phase (ASP), familial advanced sleep phase (FASP), and advanced sleep-wake phase disorder (ASWPD). This can guide clinicians on the utility of screening for extreme chronotypes both for clinical decision-making and to flag prospective participants in the study of the genetics and biology of FASP.MethodsData on morning or evening sleep schedule preference (chronotype) were collected from 2422 new patients presenting to a North American sleep center over 9.8 years. FASP was determined using a severity criterion that has previously identified dominant circadian mutations in humans. All patients were personally seen and evaluated by one of the authors (C.R.J.).ResultsOur results demonstrate an ASP prevalence of 0.33%, an FASP prevalence of 0.21%, and an ASWPD prevalence of at least 0.04%. Most cases of young-onset ASP were familial.ConclusionsAmong patients presenting to a sleep clinic, conservatively 1 out of every 300 patients will have ASP, 1 out of every 475 will have FASP, and 1 out of every 2500 will have ASWPD. This supports obtaining a routine circadian history and, for those with extreme chronotypes, obtaining a family history of circadian preference. This can optimize treatment for evening sleepiness and early morning awakening and lead to additional circadian gene discovery. We hope these findings will lead to improved treatment options for a wide range of sleep and medical disorders in the future

Sleep characteristics modify the association between genetic predisposition to obesity and anthropometric measurements in 119,679 UK Biobank participants

Background - Obesity is a multifactorial condition influenced by genetics, lifestyle and environment. Objective - To investigate whether the association between a validated genetic profile risk score for obesity (GPRS-obesity) with body mass index (BMI) and waist circumference (WC) was modified by sleep characteristics. Design - This study included cross-sectional data from 119,859 white European adults, aged 37-73 years, participating on the UK Biobank. Interactions between GPRS-obesity, and sleep characteristics (sleep duration, chronotype, day napping, and shift work) in their effects on BMI and WC were investigated. Results - The GPRS-obesity was associated with BMI (β:0.57 kg.m-2 per standard deviation (SD) increase in GPRS, [95%CI:0.55, 0.60]; P=6.3x10-207) and WC (β:1.21 cm, [1.15, 1.28]; P=4.2x10-289). There were significant interactions between GPRS-obesity and a variety of sleep characteristics in their relationship with BMI (P-interaction <0.05). In participants who slept <7 hrs or >9 hrs daily, the effect of GPRS-obesity on BMI was stronger (β:0.60 [0.54, 0.65] and 0.73 [0.49, 0.97] kg.m-2 per SD increase in GPRS, respectively) than in normal length sleepers (7-9 hours; β:0.52 [0.49, 0.55] kg.m-2 per SD). A similar pattern was observed for shiftworkers (β:0.68 [0.59, 0.77] versus 0.54 [0.51, 0.58] kg.m-2 for non-shiftworkers) and for night-shiftworkers (β:0.69 [0.56, 0.82] versus 0.55 [0.51, 0.58] kg.m-2 for non-night- shiftworkers), for those taking naps during the day (β:0.65 [0.52, 0.78] versus 0.51 [0.48, 0.55] kg.m-2 for those who never/rarely had naps) and for those with a self-reported evening chronotype (β:0.72 [0.61, 0.82] versus β:0.52 [0.47, 0.57] kg.m-2 for morning chronotype). Similar findings were obtained using WC as the outcome. Conclusions – This study shows that the association between genetic risk for obesity and phenotypic adiposity measures is exacerbated by adverse sleeping characteristics

The stimulating effect of bright light on physical performance depends on internal time.

The human circadian clock regulates the daily timing of sleep, alertness and performance and is synchronized to the 24-h day by the environmental light-dark cycle. Bright light exposure has been shown to positively affect sleepiness and alertness, yet little is known about its effects on physical performance, especially in relation to chronotype. We, therefore, exposed 43 male participants (mean age 24.5 yrs ± SD 2.3 yrs) in a randomized crossover study to 160 minutes of bright (BL: ≈ 4.420 lx) and dim light (DL: ≈ 230 lx). During the last 40 minutes of these exposures, participants performed a bicycle ergometer test. Time-of-day of the exercise sessions did not differ between the BL and DL condition. Chronotype (MSF(sc), mid-sleep time on free days corrected for oversleep due to sleep debt on workdays) was assessed by the Munich ChronoType Questionnaire (MCTQ). Total work was significantly higher in BL (median 548.4 kJ, min 411.82 kJ, max 875.20 kJ) than in DL (median 521.5 kJ, min 384.33 kJ, max 861.23 kJ) (p = 0.004) going along with increased exhaustion levels in BL (blood lactate (+12.7%, p = 0.009), heart rate (+1.8%, p = 0.031), and Borg scale ratings (+2.6%, p = 0.005)) in all participants. The differences between total work levels in BL and DL were significantly higher (p = 0.004) if participants were tested at a respectively later time point after their individual mid-sleep (chronotype). These novel results demonstrate, that timed BL exposure enhances physical performance with concomitant increase in individual strain, and is related not only to local (external) time, but also to an individual's internal time

Early-Morning and Late-Night Maximal Runs: Metabolic and Perceived Exertion Outcomes

People may exercise at the ends of their day to fit activity into their schedule; the purpose of this investigation was to determine if metabolic or perceived exertion outcomes differed between maximal runs early in the morning and late at night. After consuming a standardized, glucose drink, thirteen recreationally active individuals completed an early-morning and a late-night run on the treadmill while researchers measured metabolic (aerobic capacity and substrate usage) and perceived exertion outcomes. Point of application #1: Aerobic capacity (maximal consumption of oxygen) and the usage of fat as a fuel to support energy production during exercise were similar between runs. Point of application #2: Maximal perceived exertion (Borg’s 6-20) was similar during early-morning and late-night runs. Point of application #3: While research indicates that people may prefer activity in the morning or evening, and this might impact metabolic responses to the exercise bout, most of our participants (n=8) identified with no preference for exercising in the early-morning or late-night. Key Words: glucose; CHO shake; VO2max; fat oxidation; effor

From ZZZ\u27s to A\u27s: How Your Sleep Cycle Affects How You Study

Studying and sleeping are two essential parts of succeeding in an academic setting. The expression “the early bird gets the worm” suggests that people who wake up early garner more success in life. But why? This paper looks into the effect of a person’s chronotype (if you’re a morning person or an evening person) on study techniques and academic success. There are many different ways to study and comprehend material, with different techniques being most beneficial during different times of day. If you’ve ever felt like a study technique that works great for a friend is impossible for you to do, it may in part be related to your Morningness-Eveningness Questionnaire score. This paper will explore the circadian rhythm, morning and evening type students, and study techniques that work best for varying personalities

Siteless Survey and Intensive Data Collection in an Artifact-rich Environment: Case Studies from the Eastern Corinthia, Greece

Archaeological survey in the eastern Mediterranean has become increasingly intensive over the last 20 years, producing greater and more diverse data for smaller units of space. While complex, siteless data sets have allowed more sophisticated reconstructions of natural and cultural regional histories, the employment of more intensive methods has refocused the scope of Mediterranean surveys from region to ‘micro-region’. Such increasingly myopic approaches have been criticized for their failure to address research questions framed by a large-scale, regional perspective and the analytical categories of ‘settle- ment’ and ‘site’. This paper uses results from a survey in southern Greece to show how artifact-based approaches make valuable contributions to ‘big-picture’ historical and archaeological issues in a Mediter- ranean context