Welsh D, Richardson G S, Dement W C
Department of Psychiatry, Stanford University School of Medicine, CA 94305.
Physiol Behav. 1988;43(6):771-77. doi: 10.1016/0031-9384(88)90375-7.
Sleep/wake expression in mice varies predictably with circadian phase. Such circadian rhythms are known to depend on intact suprachiasmatic nuclei (SCN) in the hypothalamus, but the mechanism by which SCN activity modulates sleep/wake expression is unknown. This paper examines the possibility that circadian patterns of sleep/wake derive partly from circadian timing of waking behaviors that are incompatible with sleep, such as locomotor activity. Voluntary locomotor activity was restricted in five mice adapted to a running wheel by locking the wheel in place. Continuous electrographic monitoring of sleep and wakefulness over multiple circadian cycles revealed: (1) during the active phase, shorter wake bouts and more frequent bouts of sleep, resulting in greater sleep/wake fragmentation and more time spent asleep; (2) during the rest phase, a small compensatory reduction in NREM sleep; (3) reduced amplitude of circadian sleep/wake rhythms and a greater amount of sleep overall. Thus, voluntary locomotor activity has an important influence on sleep/wake expression in mice, and the normal circadian pattern of sleep/wake depends on circadian timing of activity. Previous reports of damped circadian sleep/wake rhythms in rodents may therefore be explained by coincident diminutions in locomotor activity associated with age or health status. Our results also support analogous findings in human subjects, and we propose that elderly humans may benefit from therapies that augment daytime activity.
小鼠的睡眠/觉醒表现会随着昼夜节律阶段而呈现可预测的变化。已知这种昼夜节律依赖于下丘脑完整的视交叉上核（SCN），但SCN活动调节睡眠/觉醒表现的机制尚不清楚。本文探讨了睡眠/觉醒的昼夜模式部分源自与睡眠不相容的觉醒行为（如运动活动）的昼夜定时的可能性。通过将轮子固定在原位，限制了五只适应跑轮的小鼠的自主运动活动。在多个昼夜周期内对睡眠和觉醒进行连续的脑电图监测发现：（1）在活动期，觉醒时段较短，睡眠时段更频繁，导致睡眠/觉醒碎片化程度更高，睡眠时间更长；（2）在休息期，非快速眼动睡眠有小幅代偿性减少；（3）昼夜睡眠/觉醒节律的幅度减小，总体睡眠时间增加。因此，自主运动活动对小鼠的睡眠/觉醒表现有重要影响，正常的睡眠/觉醒昼夜模式取决于活动的昼夜定时。因此，之前关于啮齿动物昼夜睡眠/觉醒节律减弱的报道可能是由于与年龄或健康状况相关的运动活动同时减少所致。我们的结果也支持在人类受试者中的类似发现，并且我们提出老年人可能会从增加白天活动的疗法中受益。
