Chapter 52.5, Problem 1R

Summary Introduction

To review:

The free-running circadian rhythm, which is entrained to 24-hour day by light.

Introduction:

Circadian rhythm is a biological clock specific to each animal, which determines sleep-wake cycle, eating, and other normal activities. It is not a 24-hour clock based on the Earth rotation on its axis, which changes day-light cycles when the Earth revolves around the Sun.