Circadian rhythm of sleep and wakefulness : estimation of genetic influences with the method of twin study

昼夜节律不同阶段的个体差异与倒班工作的适应性有关。在过去的十年中，昼夜节律睡眠障碍，表现为昼夜节律和/或节律性的异常，是一种常见的疾病。尽管个体差异在昼夜节律中的重要性已经得到了很好的认识，但个体差异产生的原因仍然不清楚，换句话说，遗传和环境对人类昼夜节律的影响还没有得到很好的研究。最近，Linkowski和他的同事研究了人体皮质醇分泌或心血管功能的昼夜变化。他们提出，基因对人类昼夜节律的几个参数有影响，然而，睡眠和清醒节律本身并未涉及。本研究旨在利用双胞胎研究的方法来评估遗传对睡眠和觉醒的几个昼夜节律参数的影响。22对双胞胎(11对同卵和11对双胞胎…更多的双胞胎)参与了这项研究。采用问卷调查法测定双胞胎合子数。他们被要求每天记录至少7天的睡眠时间。他们还要求填写关于他们的睡眠和醒来行为习惯的问卷和晨夜调查问卷(Horne和Ostberg，1976)。根据睡眠记录，作者将每15分钟的睡眠单位评分为1，将清醒状态的睡眠单位评分为0。用自相关函数估计睡眠和觉醒周期的昼夜成分的幅度，单卵和异卵双生子的平均上床时间和起床时间的类内相关系数没有差异，而用自相关函数估计的昼夜幅度的类内相关系数和被认为与核心体温相关的晨间和夜间得分在同卵双胞胎中较高。后两个变量似乎是由基因决定的。较少

Individual differences in a phase of circadian rhythm has been investigated in connection with adaptability for shift work. In the last decade, circadian rhythm sleep disorders, which shows abnormal circadian phase and/or rhythmicity, are frequently reported. Although the importance of the individual differences in circadian rhythms are well recognized, it is still unclear why the individual differences arise, in other words, genetic and environmental effects on the human circadian rhythm had not been well investigated. Recently Linkowski and co-workers investigated human circadian variations in cortisol secretion or in cardiovascular functions. They suggested genetic influences on several parameters of human circadian rhythm, however, sleep and wakefulness rhythm itself was not dealt with. This study aimed at evaluating genetical influences on several circadian rhythm parameters of sleep and wakefulness with the method of twin study.Twenty two pairs of twins (11 monozygotic and 11 diz … More ygotic twin pairs) participated in this study. Twin zygosity was determined by means of a questionnaire. They were asked to log their sleep on the daily basis for at least 7 days. They also asked to fill out the questionnaire concerning their habitual pattern of sleep and wake behavior and Morningness and Eveningness Questionnaire (Horne and Ostberg, 1976). Based on the sleep logs, the author scored each 15 min.unit of sleep as 'one' and that of wakefulness as 'zero.' Autocorrelation function was employed to estimate the amplitude of circadian component of their sleep and wakefulness cycle.Intra-class correlation coefficients for mean bedtime and rising time were not different between the monozygotic and dizygotic twin pairs, while that for circadian amplitude, estimated by autocorrelation function, and mornignness and eveningness score, which is considered to be correlated with core body temperature, were higher in the monozygotic twin pairs. The latter two variables seem to be genetically determined. Less