Biological Rhythms
All living organisms are subject to biological rhythms which influence how body systems behave. They are all governed by two factors:
- the body’s internal biological ‘clocks’ - endogenous pacemakers
- external changes in the environment - exogenous zeitgebers#
There are three types of cycles:
- Ultradian Rhythms which occur many times in 24 hours, i.e., the sleep stages cycle.
- Infradian Rhythms which take longer than 24 hours to complete, i.e., the menstrual cycle.
- Circadian Rhythms which take around 24 hours to complete, i.e., the sleep-wake cycle.