Definition

1. Noun:
   • A daily cycle of activity observed in many living organisms: A circadian rhythm is a roughly 24-hour internal biological clock that regulates cycles of sleepiness and alertness, body temperature, hormone production, and other physiological processes in living beings, including plants, animals, and humans.

Usage Examples

• Noun:
  • Disrupting your circadian rhythm by working night shifts can be harmful to your health.
  • Jet lag occurs when your circadian rhythm is out of sync with the local day-night cycle.
  • Plants also have a circadian rhythm that controls processes like leaf movement and photosynthesis.

Advanced Usage

• "to entrain a circadian rhythm": to synchronize an internal biological clock with an external cycle, such as light and dark.
  • Morning sunlight helps to entrain your circadian rhythm.
• "circadian rhythm disorder": a medical condition where a person's sleep-wake cycle is chronically misaligned.
  • Delayed Sleep Phase Syndrome is a common circadian rhythm disorder.

Variants and Related Words

• Circadian (adj): relating to or exhibiting a period of approximately 24 hours.
  • The study focused on circadian fluctuations in blood pressure.
• Biological clock: a general term for the internal mechanism that controls the periodicity of various biological functions, often synonymous with circadian rhythm in a daily context.
• Sleep-wake cycle: a specific circadian rhythm governing periods of sleep and wakefulness.

Synonyms

• Biological rhythm: a broader term for any recurring biological cycle.
• Diurnal rhythm: a rhythm with a daily cycle (though sometimes used interchangeably, "circadian" is more precise for endogenous, ~24-hour cycles).

Related Phrases

• To reset one's circadian rhythm: to adjust the internal clock to a new schedule.
  • Travelers use light therapy to reset their circadian rhythm after a long flight.
• To be governed by circadian rhythms: to have a function primarily controlled by the internal clock.
  • Hormone secretion is governed by circadian rhythms.

Related Idioms

• "Running on a different clock": (informal) having a sleep-wake schedule that is out of sync with others, often due to a disrupted circadian rhythm.
  • Since starting the night shift, I feel like I'm running on a different clock than the rest of the world.

Noun

1. a daily cycle of activity observed in many living organisms