Lavie P
Sleep Laboratory, Faculty of Medicine, Technion-Israel Institute of Technology, Haifa.
Chronobiol Int. 1989;6(1):21-8. doi: 10.3109/07420528909059139.
Studies utilizing widely different experimental techniques provided evidence that there are spontaneous ultradian cycles in arousal during the waking state. These comprised of cyclic fluctuations between increased and decreased sleep propensity with a periodicity of about 1.5 hr. Being of relatively low amplitude, these cycles are vulnerable to masking effects by a variety of experimental conditions. Masking can be exerted by varying the tonic level of arousal, by coexisting slow ultradian components which are particularly prominent during the second half of the day, or by some specific experimental conditions. Furthermore, increased sleepiness was shown to enhance the slow ultradian components and suppress the 1.5-hr cycles in EEG indices of arousal on the one hand, and to emphasize the 1.5-hr cycles in motor activity and reaction time performance on the other hand. Much more attention should be paid to the problem of masking of ultradian cycles in arousal. Recognizing the sources and reasons for masking will advance our knowledge of the characteristics of these cycles and their function.
利用广泛不同实验技术的研究提供了证据，表明在清醒状态下觉醒存在自发的超日周期。这些周期包括睡眠倾向增加和减少之间的周期性波动，周期约为1.5小时。由于振幅相对较低，这些周期容易受到各种实验条件的掩盖效应影响。掩盖可以通过改变觉醒的紧张水平、通过共存的缓慢超日成分（在一天的后半段尤为突出）或通过某些特定实验条件来施加。此外，一方面，困倦增加被证明会增强缓慢超日成分并抑制脑电图觉醒指标中的1.5小时周期，另一方面，会突出运动活动和反应时间表现中的1.5小时周期。对于觉醒中超日周期的掩盖问题应给予更多关注。认识到掩盖的来源和原因将推进我们对这些周期的特征及其功能的了解。
