Biological Rhythms

Circadian rhythms

Biological rhythms with cycles that generally occur once every 24 hours, such as the sleep-wake cycle.

Infradian rhythms

Biological rhythms with cycles that occur less than once every day, like the menstrual cycle.

Ultradian rhythms

Biological rhythms with cycles that occur more than once every 24 hours, for example, the sleep cycle with stages of light and deep sleep.

Endogenous pacemakers

Genetically determined biological structures and mechanisms within the body that regulate some aspects of biological rhythms.

Suprachiasmatic nucleus (SCN)

Part of the hypothalamus acting as an internal clock to maintain an approximate 24-hour sleep-wake cycle, sensitive to light and regulating melatonin secretion.

Exogenous Zeitgebers

External influences acting as prompts triggering biological rhythms, with light being a crucial zeitgeber.

Jet lag

Disruption of the sleep-wake cycle due to out-of-sync endogenous pacemakers and exogenous zeitgebers, often experienced during rapid travel across time zones.

Adaptation to jet lag

The process of synchronising to a new time zone, which may take about a week, involving strategies like forcing oneself to stay awake.

Limitations of biological rhythm research

Challenges in generalizing findings from animal studies to humans, the impact of individual differences, and the need for further exploration on lifestyle effects on biological rhythms.