Central nervous system and peripheral immune functions and the sleep-wake system.

This paper reviews the relationship of aspects of the immune system to the sleep-wake system in animals and humans. In addition to the influence of certain cytokines such as interleukin-1 (IL-1) on the sleeping-waking brain, circadian measures of plasma IL-1 and peripheral immune cellular functions, for example, natural killer cell activities and cortisol are related to the sleep-wake system in humans. Changes in the circadian patterns of immune functions over the menstrual cycle are associated with the amount of progesterone and slow wave sleep. The harmonious inter-relationship of the circadian pattern of the immune, endocrine and sleep-wake systems may be important in the cause and functions of sleep.