The circadian clock and behavior

Temporal organization is a fundamental feature of all living systems. Timin g is essential for development. growth and differentiation and in the matur e organism, it is essential to maintain normal physiology and behavior. The biological entity that permits an organism's day/night organization is the circadian system. In the following, we describe how daily or circadian act ivity is measured in mice, and what such activity measurements can tell us about the state of the animal. (C) 2001 Elsevier Science B.V. All rights re served.