Biosocial behaviour cycles: a field study in an East Indian village community.

Abstract

SummaryMany physiological functions of the human body as well as human behaviour are regulated by endogenous rhythms. While circadian rhythms with periods of about 24 hr serve to adjust body functions and patterns of behaviour to the geophysical day/night cycle, intrinsic rhythms with shorter periods, called ultradian cycles, subdivide the 24-hr interval. For example, motor activity, perception and cognitive style are influenced by an intrinsic cycle of about 1½ hr. Despite numerous laboratory studies, the functions of ultradian rhythms are as yet unknown. In this field study, endogenous short-term cycles were observed in the daily behavioural patterns of illiterate individuals living without artificial time-cues in a small East Indian village community. Time series analysis of the result provides additional evidence that behavioural patterns of adults as well as infants and children living under natural conditions may be regulated by intrinsic rhythms with period intervals of 1–3 hr. Furthermore ultradian behaviour cycles in single subjects can be synchronized within a common time-frame. This suggests that intrinsic ultradian cycles may serve to organize daily behaviour patterns for optimal co-ordination and satisfaction of individual and common demands.