Fischer Dorothee, Lombardi David A, Marucci-Wellman Helen, Roenneberg Till
Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States of America.
Center for Injury Epidemiology, Liberty Mutual Research Institute for Safety, Hopkinton, Massachusetts, United States of America.
PLoS One. 2017 Jun 21;12(6):e0178782. doi: 10.1371/journal.pone.0178782. eCollection 2017.
An individual's chronotype reflects how the circadian system embeds itself into the 24-h day with rhythms in physiology, cognition and behavior occurring accordingly earlier or later. In view of an increasing number of people working at unusual times and linked health and safety risks, the wide range in human chronotypes may provide opportunities to allow people to work (and sleep) at times that are in synch with their circadian physiology. We aimed at estimating the distribution of chronotypes in the US population by age and sex. Twelve years (2003-2014) of pooled diary data from the American Time Use Survey were used to calculate chronotype based on mid-point of sleep on weekends (MSFWe, n = 53,689). We observed a near-normal distribution overall and within each age group. The distribution's mean value is systematically different with age, shifting later during adolescence, showing a peak in 'lateness' at ~19 years, and shifting earlier thereafter. Men are typically later chronotypes than women before 40, but earlier types after 40. The greatest differences are observed between 15 and 25 for both sexes, equaling more than 50% of the total chronotype difference across all age groups. The variability in chronotype decreases with age, but is generally higher in males than females. This is the first study to estimate the distribution and prevalence of individual chronotypes in the US population based on a large-scale, nationally representative sample. Our finding that adolescents are on average the latest chronotypes supports delaying school start times to benefit their sleep and circadian alignment. The generally wide range in chronotypes may provide opportunities for tailored work schedules by matching external and internal time, potentially decreasing long- and short-term health and safety risks.
个体的昼夜节律类型反映了昼夜节律系统如何将自身融入24小时的一天之中，相应地，生理、认知和行为节律会提前或推迟出现。鉴于越来越多的人在非常规时间工作以及相关的健康和安全风险，人类昼夜节律类型的广泛差异可能为人们提供机会，使其能够在与自身昼夜节律生理同步的时间工作（和睡眠）。我们旨在按年龄和性别估算美国人群中昼夜节律类型的分布情况。利用美国时间使用调查12年（2003 - 2014年）汇总的日记数据，根据周末睡眠时间中点（MSFWe，n = 53,689）计算昼夜节律类型。我们观察到总体以及每个年龄组内的分布接近正态分布。分布的平均值随年龄有系统性差异，在青春期后期向后推移，在约19岁时出现“晚睡”高峰，此后又提前。40岁之前，男性的昼夜节律类型通常比女性更偏晚，但40岁之后则更早。在15至25岁之间，男女的差异最为显著，超过了所有年龄组昼夜节律类型总差异的50%。昼夜节律类型的变异性随年龄降低，但总体上男性高于女性。这是第一项基于大规模、具有全国代表性样本估算美国人群中个体昼夜节律类型分布和患病率的研究。我们发现青少年平均昼夜节律类型最晚，这支持推迟上学时间，以利于他们的睡眠和昼夜节律同步。昼夜节律类型通常差异较大，这可能为通过匹配外部和内部时间来制定个性化工作时间表提供机会，从而潜在地降低长期和短期的健康及安全风险。
