Biological Rhythms (Biological)

Biological Rhythms (Biological)

Biological Rhythms

Circadian Rhythms

  • Circadian rhythms are the body’s internal 24-hour clock that regulates our sleep-wake cycle.
  • Key examples include the sleep-wake cycle and body temperature and hormone release patterns throughout the day.
  • The suprachiasmatic nucleus (SCN) in the hypothalamus is the primary regulator of circadian rhythms.
  • Zeitgebers, or external influences such as light or temperature, help synchronise our circadian rhythms with our environment.

Ultradian Rhythms

  • These are shorter rhythms that occur more than once daily. Sleep stages, like REM and Non-REM sleep which cycle every 90-120 minutes, are examples of ultradian rhythms.
  • Other ultradian rhythms include feeding patterns and the release of certain hormones like insulin.

Infradian Rhythms

  • These are longer rhythms that occur less than once per day. Menstrual cycles and seasonal affective disorder (SAD), which follow yearly cycles, are examples of infradian rhythms.
  • The pineal gland’s release of melatonin, which affects our sleep-wake cycle, can also be influenced by seasonal changes, thus showing infradian rhythms.

Disruption of biological rhythms

  • Disruption of these biological rhythms due to factors like shift work, jet lag, or lifestyle changes can lead to various psychological and physiological problems.
  • Jet lag, for example, leads to symptoms like fatigue, disorientation, and insomnia due to the discrepancy between our internal biological clock and the external environment.
  • Shift work can disrupt our circadian rhythms and lead to difficulties in sleeping, decreased alertness, and other health issues.

Biological Rhythms and the Endogenous Pacemaker

  • Our biological rhythms are influenced by endogenous pacemakers, internal biological clocks that regulate these rhythms.
  • Endogenous pacemakers interact with external cues like light (zeitgebers) to maintain our biological rhythms.

Remember to memorise key terms like circadian, ultradian, infradian rhythms, zeitgebers, and endogenous pacemakers as these are critical concepts in understanding biological rhythms.