Innovations in Biotechnology and Medical Sciences

Understanding Ultradian Rhythms: The Cycle of Life


From UPSC perspective, the following things are important :

Prelims level: Ultradian vs. Circadian Rhythms and key difference between them

Mains level: NA


  • Life on Earth is characterized by cyclical processes that sustain and enhance survival, with one such fundamental process being ultradian rhythms.
  • Ultradian rhythms are distinct from circadian rhythms and refer to biological cycles that occur more frequently than once every 24 hours, governing essential physiological functions.

Ultradian vs. Circadian Rhythms

Ultradian Rhythms Circadian Rhythms
Definition Repeat at intervals of less than 24 hours. Repeat approximately every 24 hours.
Duration Shorter cycles, typically minutes to a few hours. Longer cycles, around 24 hours.
Examples Sleep cycles, heart rate variability, hormone release. Sleep-wake cycle, body temperature regulation.
Influence Impact physiological processes within a single day. Regulate sleep-wake patterns, hormone release, etc.
Importance Essential for various bodily functions and processes. Crucial for maintaining overall health and well-being.
Disruption Effects Interruption can lead to fatigue or mood swings. Disruption can cause sleep disorders or mood disorders.

Key Characteristics of Ultradian Rhythms

  • Frequency: Ultradian rhythms recur more frequently than circadian rhythms, impacting various biological processes.
  • Physiological Patterns: These rhythms regulate heartbeat, breathing, hormonal release, and brain-wave activity, ensuring proper functioning of living organisms.


  • Sleep Cycle: A well-known example of ultradian rhythm is the sleep cycle, which comprises alternating periods of REM (Rapid Eye Movement) and non-REM sleep, typically lasting around 90 minutes each.
  • REM and Non-REM Sleep: REM sleep involves dreaming, while non-REM sleep is essential for physical restoration and memory consolidation.

Role in Hormonal Regulation

  • Pulsatile Hormone Secretion: Ultradian rhythms influence the pulsatile secretion of hormones like growth hormone, cortisol, and insulin throughout the day.
  • Metabolism and Stress Response: These hormonal fluctuations are crucial for regulating metabolism, energy levels, and responses to stress, ensuring overall well-being.

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