Human circadian rhythms.

Publisher Website
Google Scholar
Abstract
Many functions show circadian rhythmicity, but this is often merely impressed by external rhythm of habit or environment. There is, however, a circadian clock, which may be placed tentatively in the region of the hypothalamus, influencing a variety of functions through many channels, known and unknown, and it may itself be influenced by various environmental stimuli. When the social environment contributes, the cortex is presumably involved; but the clock does not seem to reside there, since temperature and eosiniphil rhythms persist during regression induced by intensive electroshock therapy, when neurological examination indicates a lack of cortical function. There is no compelling evidence for the existence of more than one clock; only the demonstration of 2 rhythms of slightly different cycle length, neither corresponding to an external rhythm, could prove this. Conversely, it is perfectly conceivable that endogenous rhythmicity is present at many levels of organization as, for instance, in many or all of the functions indicated in this study. Each would normally be entrained by another rhythm, external or internal, thus securing the customary integration and synchronization of different functions, but leaving varied possibilities for disturbance that have hardly yet been explored in man.

This publication has 71 references indexed in Scilit: