What is Circadian Rhythm and How it Works?
The circadian rhythm is your body’s internal 24-hour biological clock that regulates many important functions, especially sleep and wake cycles. It’s controlled by a small part of the brain called the suprachiasmatic nucleus (SCN), located in the hypothalamus, and it responds to light and darkness in your environment.
Here’s a detailed breakdown:
How It Works
Your circadian rhythm uses environmental cues — mainly sunlight — to determine when to wake up, feel alert, or get sleepy.
In the morning, exposure to natural light signals the brain to produce cortisol, which boosts energy and alertness.
As the day ends and it gets darker, your body increases melatonin production, a hormone that promotes relaxation and sleep.
Key Functions It Regulates
Sleep-wake cycle → Decides when you naturally feel awake or tired.
Hormone release → Regulates melatonin, cortisol, and growth hormones.
Body temperature → Naturally drops at night to prepare you for sleep.
Metabolism & digestion → Influences appetite and energy use.
Mental performance → Peak cognitive abilities align with your circadian rhythm.
Disruption Effects
When your circadian rhythm is out of sync — due to late-night screen use, shift work, jet lag, or poor sleep hygiene — it can lead to:
Trouble falling or staying asleep
Daytime fatigue
Mood swings and irritability
Weakened immune function
Long-term risks like obesity, diabetes, and heart disease
How to Support a Healthy Circadian Rhythm
Get morning sunlight to “reset” your internal clock.
Keep a consistent sleep schedule, even on weekends.
Limit screens at night to reduce blue light exposure.
Dim lights in the evening to encourage melatonin release.
Avoid caffeine and heavy meals close to bedtime.