DIURNAL RHYTHMS OF KETO- AND KETOGENIC STEROID EXCRETION AND THE ADAPTATION TO CHANGES OF THE ACTIVITY-SLEEP ROUTINE

Abstract

SUMMARY: 1. An investigation of the diurnal rhythms of keto- and ketogenic steroid excretion has been carried out in four human subjects. The subjects lived, under standardized conditions of diet, activity and lighting, in Spitsbergen where 24 hr. daylight persists during the summer. 2. A study of the adaptation of their rhythms to a reversed activity-sleep and light-darkness schedule has been made, and of the subsequent re-adaptation to normal schedules. 3. Adaptation of the ketosteroid rhythm occurred in 2 days and of the ketogenic steroid rhythm in 8 days. 4. The ketosteroid excretory rhythm may depend immediately, and the ketogenic steroid rhythm ultimately, upon habit and environment. 5. Evidence has been presented to suggest that the ketogenic steroid rhythm is dependent upon the synchronization of pituitary and adrenal responsiveness. During the reversal of rhythm, adrenocortical activity takes place initially in the early 'evening' and 'night', occurring progressively earlier each day until it synchronizes with the new time scale. 6. The significance of these findings is discussed.