Misalignment between an individual’s circadian phase and his/her environment due to social imposition is called social jetlag (SJL). SJL has emerged as a public health concern, as it contributes to an unhealthy lifestyle and adverse health outcomes. This study aimed to elucidate the percentage of SJL in a large Japanese population using the Japanese version of the Munich ChronoType Questionnaire (MCTQ). A total of 10,000 participants responded to a web-based cross-sectional survey, and the final sample comprised 3708 participants (60.1% male; average age 45.1 [SD 13.4] years). SJL was measured by subtracting each participant’s midpoint of sleep on workdays from their midpoint of sleep on free days. The average [SD] absolute SJL (SJLabs) value was 0.91 [0.89] hours, and the percentage of participants with SLJabs of more than 1 h was 40.1%. Our data also showed that SJLabs becomes progressively smaller with advancing age. A considerable number of participants of our Japanese population showed differences in sleep behavior between workdays and free days. Young people in particular commonly oversleep on free days to compensate for the sleep debt accumulated over the workweek because of their late chronotype.

中文翻译：

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日本社会时差调查：一项全国性、横断面的互联网调查

由于社会强加而导致的个人昼夜节律与其环境之间的错位称为社会时差 (SJL)。SJL 已成为一个公共卫生问题，因为它会导致不健康的生活方式和不利的健康结果。本研究旨在使用日文版的慕尼黑 ChronoType 问卷 (MCTQ) 阐明大量日本人口中 SJL 的百分比。共有 10,000 名参与者参与了一项基于网络的横断面调查，最终样本包括 3708 名参与者（60.1% 男性；平均年龄 45.1 [SD 13.4] 岁）。SJL 是通过每个参与者在工作日的睡眠中点减去他们在空闲日的睡眠中点来衡量的。平均 [SD] 绝对 SJL (SJLabs) 值为 0.91 [0.89] 小时，SLJabs 超过 1 小时的参与者百分比为 40.1%。我们的数据还显示，随着年龄的增长，SJLabs 变得越来越小。我们日本人口中的相当多的参与者在工作日和空闲日之间表现出睡眠行为的差异。尤其是年轻人，他们通常在空闲时间睡过头，以弥补由于他们晚睡型而在工作周内积累的睡眠债务。