Strogatz S H, Kronauer R E, Czeisler C A
Am J Physiol. 1987 Jul;253(1 Pt 2):R172-8. doi: 10.1152/ajpregu.1987.253.1.R172.
The human circadian pacemaker modulates our desire and ability to fall asleep at different times of day. To study this circadian component of sleep tendency, we have analyzed the sleep-wake patterns recorded from 15 free-running subjects in whom the sleep-wake cycle spontaneously desynchronized from the circadian rhythm of body temperature. The analysis indicates that the distribution of sleep onsets during free run is bimodal, with one peak at the temperature trough and, contrary to previous reports, a second peak 9-10 h later. Furthermore, there are two consistent zones in the circadian temperature cycle during which normal subjects rarely fall asleep. We hypothesize that this bimodal rhythm of sleep tendency, revealed under free-running conditions, maintains the same fixed phase relation to the circadian temperature cycle during 24-h entrainment. This would imply that normally entrained individuals should experience a peak of sleep tendency in the midafternoon and a zone of minimal sleep tendency approximately 1-3 h before habitual bedtime. Our temporal isolation data thereby account quantitatively for the timing of the afternoon siesta and suggest that malfunctions of the phasing of the circadian pacemaker may underlie the insomnia associated with sleep-scheduling disorders.
人体昼夜节律起搏器调节我们在一天中不同时间入睡的欲望和能力。为了研究睡眠倾向的这种昼夜节律成分，我们分析了15名自由运转受试者的睡眠-清醒模式，这些受试者的睡眠-清醒周期与体温的昼夜节律自发地不同步。分析表明，自由运转期间睡眠开始时间的分布是双峰的，一个峰值出现在体温低谷时，与之前的报道相反，另一个峰值在9-10小时后。此外，在昼夜体温周期中有两个一致的时间段，正常受试者在这些时间段很少入睡。我们假设，在自由运转条件下揭示的这种睡眠倾向双峰节律，在24小时的同步过程中与昼夜体温周期保持相同的固定相位关系。这意味着正常同步的个体应该在下午中段经历睡眠倾向的峰值，以及在习惯就寝时间前大约1-3小时经历睡眠倾向最小的时间段。因此，我们的时间隔离数据定量地解释了午睡的时间，并表明昼夜节律起搏器相位的故障可能是与睡眠安排障碍相关的失眠的基础。
