The circadian rhythm is the body’s internal 24 hour clock that regulates a wide array of physiological processes. From sleep and hormone release to digestion, immune function and cell repair, the circadian system helps the body stay in sync with the natural cycles of day and night.
A well aligned circadian rhythm supports mental clarity, metabolic health and emotional stability. Disruption of this rhythm, however, has been linked to faster biological aging and increased risk of chronic disease.
How circadian rhythms work
Circadian rhythms are governed by a group of neurons in the brain called the suprachiasmatic nucleus (SCN), located in the hypothalamus. This “master clock” is synchronized by external cues, primarily light and darkness and sends signals to regulate other peripheral clocks throughout the body, in organs, muscles and even immune cells.
Light exposure in the morning resets the clock daily, while darkness signals the body to release melatonin and prepare for rest. The SCN works in harmony with behavioral cues like eating, activity and sleep to coordinate physiological rhythms across all systems.
Key functions regulated by circadian rhythm
The circadian system orchestrates the timing of:
- Sleep wake cycles: including melatonin secretion and sleep depth;
- Hormone rhythms: such as cortisol (alertness), insulin (glucose control) and growth hormone (tissue repair);
- Body temperature: which affects sleep onset and performance;
- Digestion and metabolism: including nutrient absorption and energy use;
- Immune activity and inflammation control: especially at night during rest;
- Cellular repair and detoxification: timed for overnight optimization.
Every organ system has its own internal rhythm and the circadian clock helps them function in harmony and at the right time.
Circadian disruption and its effects
When circadian rhythms are disrupted, the body can fall out of sync with its environment. Common disruptors include:
- Irregular sleep schedules;
- Artificial light exposure at night;
- Night shift work or jet lag;
- Late night eating;
- Excessive caffeine, alcohol or screen use before bedtime.
These disruptions are associated with:
- Metabolic dysfunction (insulin resistance, weight gain);
- Sleep disorders and fatigue;
- Mood instability and anxiety;
- Cognitive decline and neurodegenerative risk;
- Immune dysregulation and chronic inflammation.
Over time, circadian misalignment can contribute to accelerated aging, especially by impairing DNA repair, mitochondrial function and hormonal balance.
How to support circadian alignment
We can support our body’s natural clock by:
- Morning light exposure: spend 15–30 minutes outdoors in the morning to signal wakefulness and set the day’s rhythm;
- Sleep consistency: go to bed and wake up at the same time each day, even on weekends;
- Time restricted eating: finish eating 2–3 hours before bedtime, ideally within a 10–12 hour daytime window;
- Minimize disruptors at night: avoid screens, bright lights, caffeine and alcohol in the evening. Use dim, warm lighting after sunset to support melatonin release;
- Optimize our sleep environment: keep our bedroom cool, dark and quiet. Establish a calming bedtime routine to prepare the nervous system for rest.
The circadian rhythm is one of the bodys most fundamental biological systems, influencing everything from metabolism and memory to immunity and repair. When in sync, it promotes energy, clarity and long term health. When out of sync, it can accelerate aging and increase the risk of chronic disease.
By aligning our lifestyle with our natural rhythms, through light, food, sleep and movement, we can support our biological clock and lay the foundation for a longer, healthier life.
