Endocrine Abstracts

Circadian rhythms are cycles of behaviour and physiology that persist with a period of approximately (circa-) one day (-dian) when an individual is held in temporal isolation. They permeate all levels of biological activity, from gene expression and hormone secretion to cognitive ability. These daily rhythms are co-ordinated by a hypothalamic pacemaker, the suprachiasmatic nuclei (SCN). Individual SCN neurons are competent circadian pacemakers, synchronised to solar time by re...