Skip to main content

SomnoWell Sleep Clinic

Vertical-removebg
Menu
BOOK NOW

Circadian Rhythm: Your Body’s Internal Clock

The circadian rhythm is the body’s 24-hour internal clock, regulating when you feel awake and when you feel sleepy [1]. It also influences hormones, body temperature, digestion, and mood. A well-synchronized circadian rhythm supports good sleep quality and overall health.

🟩 How It Works

  • The suprachiasmatic nucleus (SCN) in the hypothalamus acts as the “master clock”.

  • Light is the strongest signal: daylight resets the clock each morning [2].

  • Hormones: melatonin rises at night to promote sleep; cortisol peaks in the morning to promote alertness.

  • Other factors like meals, exercise, and social activities also fine-tune the rhythm.

🟩 Chronotypes (“Morning Larks” vs “Night Owls”)

  • Morning types feel alert early and get sleepy sooner.

  • Evening types prefer staying up late and waking later.

  • Genetics play a major role, but age and lifestyle also influence chronotype [3].

  • Knowing your chronotype can help align work and sleep schedules for better health.

🟩 When the Rhythm Is Disrupted

  • Shift work: misalignment between work schedule and circadian rhythm increases risk of fatigue, heart disease, diabetes [4].

  • Jet lag: temporary disruption caused by crossing time zones; usually takes days to re-synchronize.

  • Social jetlag: mismatch between weekday and weekend sleep schedules, common in students and young adults [5].

  • Poor alignment may contribute to mood disorders, metabolic syndrome, and reduced immune function.

🟦 Tips for a Healthy Circadian Rhythm

  • Get morning sunlight exposure soon after waking.

  • Maintain a consistent sleep-wake schedule, even on weekends.

  • Avoid bright light (especially blue light from screens) before bedtime.

  • Time meals and exercise earlier in the day if possible.

  • Create a dark, cool, and quiet sleep environment.

References:

  1. Takahashi JS. Transcriptional architecture of the mammalian circadian clock. Nat Rev Genet. 2017.

  2. Czeisler CA, et al. Stability, precision, and near-24-hour period of the human circadian pacemaker. Science. 1999.

  3. Roenneberg T, et al. Chronotype and social jetlag: a (self-) critical review. Biology. 2019.

  4. Kecklund G, Axelsson J. Health consequences of shift work and insufficient sleep. BMJ. 2016.

  5. Wittmann M, et al. Social jetlag: misalignment of biological and social time. Chronobiol Int. 2006.