Dual oscillator structure of human biological clock: Oscillation coupling between the circadian rhythms and sleep-wake cycle and the sites of oscillation

1.睡眠-觉醒节律的非光性夹带1)将睡眠-觉醒节律夹带到非光觉性节律的瞬时阶段受试者按照8天的睡眠-觉醒时间表，然后是4天的自由奔跑。在大多数受试者中，血浆褪黑素节律在强制节律过程中显示出相延时移，这表明褪黑素节律未能进入非光时代。另一方面，在所有受试者(n=8)中，睡眠-觉醒节律从强制时间表允许睡眠的阶段开始变为自由节律，这表明睡眠-觉醒节律已经被非光时间表所破坏。为了了解睡眠-觉醒节律进入非光时间表所需的周期，强制时间表的暴露时间缩短到4天，再缩短到1天。结果，一半受试者的睡眠-觉醒周期被强制安排为4天，而另一半受试者的睡眠-觉醒周期为…更不用说了。在1天的强制时间表中，所有受试者的睡眠-觉醒节律都没有被缠绕。2)褪黑激素节律和睡眠-觉醒节律之间的内部同步性的重建。强迫节律终止后，通过睡眠-觉醒节律的提前或延迟相移，在几天内使内部去同步的睡眠-觉醒节律和褪黑素节律重新同步。相移的大小和方向取决于入睡前与血浆褪黑素节律峰值之间的相移关系。也就是说，当两种节律的相位差为2~4h时，没有发生相移。而相位差为8~12h，相移超过6h。这些发现有力地表明，睡眠-觉醒和血浆褪黑素节律之间存在着振荡的相互作用。人SCN的光反应性用功能磁共振方法研究了人SCN的光反应性。对8名受试者进行1000lx照射，观察SCN区神经元活动的变化。只有一个人对光刺激有反应，而其他人没有，这表明SCN对光的反应在人类中不是很强。较少

1. Non-photic entrainment of sleep-wake rhythm1) Transient periods for entrainment of sleep-wake rhythm to the non-photic zeitgeberThe human subjects were foreced to the sleep-wake schedule for 8 days with was followed by a free-run session of 4 days. In most subjects, plasma melatonin rhythms demonstrated phase-delay shifts during the forced schedule, indicating that the melatonin rhythm failed to entrain to the non-photic zeitgeber. On the other hand, in all subjects examined (n=8) the sleep-wake rhythm started to free-rum from the phase where sleep was allowed by the forced schedule, indicating that the sleep-wake rhythm had been etrained by the non-photic schedule.In order to know the cycle needed for the sleep-wake rhythm to entrain to the non-photic zeitgeber, the exposere period to the forced schedule was shortened to 4 days and further 1 day. As a result, the sleep-wake cycle of a half of the subjects entrained to the forced schedule of 4 days, while that of the other half did … More not. To the forced schedule of 1 day, the sleep-wake rhythm in all subjects failed to entrain. The findings indicate that there was a transient period of several days for the entrainment, and that the entrainment was an oscillatory nature.2) Reestablishment of internal synchronization between the melatonin rhythm and sleep-wake rhythmAfter the forced scheduled was termimated, the internally decynchronized sleep-wake and melatonin rhythms were resynchronized in a few days by means of phase-advance or -delay shifts of sleep-wake rhythm. The amount as well as the direction of phase shift depended on the phase-relashionship before the phase-shift between the sleep-onset and the peak of plasma melatonin rhythm. Namely, when the phase difference of the two rhythms was 2 to 4 hours, there was no phase-shift occurred . On the other hand, the phase difference was 8 to 12 hours, the procuded phase-shift exceeded 6 hours. These findings strongly suggested that there was an oscillatory interaction between the sleep-wake and plasma melatonin rhythms.2. Light responsiveness of human SCNLight responsiveness of the human SCN was studied by means of functional MRI. Eight subjects were exposed to light of 1,000 lx and the changes of neuronal activites in the SCN region were monitored. Only one responded to light stimuli but others not, suggesting that that the SCN response to light is not very strong in humans. Less