Richardson Gary S
Division of Sleep Medicine, Henry Ford Hospital, Detroit, MI 48202, USA.
J Clin Psychiatry. 2005;66 Suppl 9:3-9; quiz 42-3.
The human circadian system regulates rhythmicity in the human body and establishes normal sleep and wake phases. The suprachiasmatic nuclei (SCN), located in the hypothalamus above the optic chiasm, make up the human pacemaker known as the circadian or biological clock, but other essential parts of the circadian system include the pineal gland, retina, and retinohypothalamic tract. The importance of light in resetting the intrinsic human circadian cycle, the intrinsic period of which is slightly longer than 24 hours, ensures that the human cycle will stay entrained to the earth's 24-hour daily cycle. Within the SCN neurons, circadian rhythmicity is generated by the regular transcription of proteins. Since the circadian system is the foundation of the sleep-wake cycle, disorders and abnormalities in sleep are often connected with disorders or abnormalities in the circadian system. Circadian rhythm sleep disorders, such as jet lag syndrome and shift work sleep disorder, are those specifically attributed to dysfunctions or insufficiencies in the circadian system. Taking into consideration the preeminence of the circadian clock in timing sleep, it is likely that other sleep disorders, such as insomnia, are also linked to circadian system abnormalities.
人体昼夜节律系统调节人体的节律性，并建立正常的睡眠和觉醒阶段。位于视交叉上方下丘脑的视交叉上核（SCN）构成了被称为昼夜节律或生物钟的人体起搏器，但昼夜节律系统的其他重要部分包括松果体、视网膜和视网膜下丘脑束。光在重置人体内在昼夜节律周期（其内在周期略长于24小时）方面的重要性，确保了人体周期与地球24小时的日常周期保持同步。在SCN神经元内，昼夜节律性是由蛋白质的定期转录产生的。由于昼夜节律系统是睡眠-觉醒周期的基础，睡眠障碍和异常通常与昼夜节律系统的紊乱或异常有关。昼夜节律性睡眠障碍，如时差综合征和轮班工作睡眠障碍，是那些特别归因于昼夜节律系统功能障碍或不足的疾病。考虑到昼夜节律时钟在睡眠定时方面的首要地位，其他睡眠障碍，如失眠，也可能与昼夜节律系统异常有关。
