Social Jetlag and Obesity

Abstract

Obesity has reached crisis proportions in industrialized societies. Many factors converge to yield increased body mass index (BMI). Among these is sleep duration. The circadian clock controls sleep timing through the process of entrainment. Chronotype describes individual differences in sleep timing, and it is determined by genetic background, age, sex, and environment (e.g., light exposure). Social jetlag quantifies the discrepancy that often arises between circadian and social clocks, which results in chronic sleep loss. The circadian clock also regulates energy homeostasis, and its disruption-as with social jetlag-may contribute to weight-related pathologies. Here, we report the results from a large-scale epidemiological study, showing that, beyond sleep duration, social jetlag is associated with increased BMI. Our results demonstrate that living "against the clock" may be a factor contributing to the epidemic of obesity. This is of key importance in pending discussions on the implementation of Daylight Saving Time and on work or school times, which all contribute to the amount of social jetlag accrued by an individual. Our data suggest that improving the correspondence between biological and social clocks will contribute to the management of obesity.

Genetics of Human Sleep Behavioral Phenotypes

“…For the short sleep phenotype, we select affected individuals that require less than 6.5 h of sleep per night, with normal sleep onset time. It should be noted that a significant portion of the population exhibit "social sleep deprivation" (also called "social jetlag" in the original report) on their workdays due to work and/or social obligations (Roenneberg et al, 2012). However, as opposed to natural short sleepers, those individuals tend to make up for their sleep debt during nonworkdays, and they also have stronger sleep drive during the day (Roenneberg, 2013).…”

“…These individuals tend to sleep more during the nonwork days to make up for the sleep debt (Roenneberg, 2013;Roenneberg et al, 2012). Since the degree of sleep deprivation varies among individuals, the Epworth Sleepiness Scale or Karolinska Sleepiness Scale is useful in gauging whether a person is actually getting enough sleep (Akerstedt & Gillberg, 1990;Johns, 2002).…”

“…It is known, nevertheless, that sufficient and consolidated sleep of good quality is crucial for proper physical and cognitive performance in the vigilant awake state. Adverse effects due to sleep deprivation or circadian desynchrony include increased risks of a spectrum of health problems from obesity (Roenneberg, Allebrandt, Merrow, & Vetter, 2012) and cancer (Haus & Smolensky, 2013) to psychiatric disorders (Colten, Altevogt, & Institute of Medicine (U.S.). Committee on Sleep Medicine and Research, 2006).…”

“…Committee on Sleep Medicine and Research, 2006). Alarming epidemiologic data show a steady decrease of nightly sleep duration in American adults over that past 50 years (Colten et al, 2006;Kraus & Rabin, 2012) and a significant discrepancy of sleep duration between work days and nonwork days (social sleep deprivation; Roenneberg et al, 2012). It is estimated that 50-70 million of people chronically suffer from sleep-related problems in the United States alone (Colten et al, 2006), and long-term burden of these sleep pathologies is conceivably enormous.…”

Chronobiology: Stepping out of time

“…Many modern workers effectively live on two different timetables -one enforced by their weekday alarm clock, and the other aligned to their weekend socializing and 'sleeping in' -resulting in disruption that he has dubbed 'social jetlag' 3 . "In most people, it looks as if they were travelling from Europe to the United States on a Friday evening and back on a Monday morning, because their displacement is so large, " says Roenneberg.…”