Biological Rhythms

Abstract

All living creatures show rhythmic changes in their physiology and behavior. Table 7-1 lists some examples of physiological rhythms in the human. Biological rhythms, like physical rhythms such as sound waves, can be described by four properties (Fig. 7-1):

• 1. Phase defines a specific time within the cycle (e.g., the maximum or the minimum).

• 2. Period defines the duration of the rhythm as measured between two identical phases (e.g., between successive maxima).

• 3. Frequency defines the rate of the rhythm as measured by the number of cycles per unit of time.

• 4. Amplitude defines the magnitude of the rhythm as measured by the difference between the maximum phase and the mean between the maximum and minimum phases (Fig. 7-1, horizontal line).