Chronobiology is the study of biological rhythms which are governed by endogenous pacemakers and entrained by geophysical correlates of the environment. Thus, there are circadian (daily), lunar-monthly and circannual rhythms characterizing the biology and behaviour of organisms. Erwin Bunning, an eminent biologist, wrote in 1973, ‘As recently as 15 to 20 years ago, to proclaim the existence of an endogenous diurnal rhythm was regarded, even by well-known ...
