Circadian Rhythm: How to Reset Your Internal Clock to Optimize Health

Have you ever experienced jet lag or struggled to adjust to a new work schedule? These challenges stem from disruptions to your circadian rhythm — aka circadian timing system — your body’s natural 24-hour internal clock.

This complex system regulates various functions, from sleep patterns to hormone release, influencing your overall health and well-being.

In our fast-paced world, where sleep often takes a back seat to productivity and entertainment, understanding the importance of circadian rhythm is crucial. This natural, internal process regulates our sleep-wake cycle and influences various bodily functions.

Let’s examine what circadian rhythm is, how it works, its connection to sleep and strategies for maintaining a healthy rhythm.

What Is Circadian Rhythm?

Circadian rhythm refers to the 24-hour cycle that regulates various physiological processes in living organisms, including humans. Derived from the Latin words “circa” (meaning “around”) and “diem” (meaning “day”), circadian rhythms are driven by internal biological clocks and external cues, such as light and temperature.

Imagine your body having a built-in timer. That’s essentially what a circadian rhythm is.

It’s a 24-hour cycle that governs various biological processes, including:

• sleep-wake cycles
• hormone production
• cell regeneration
• body temperature
• digestion and metabolism
• immune system
• brain functioning
• reaction to stress

This internal clock isn’t dependent on external cues, but it synchronizes with the environment, primarily through light exposure.

There is also the infradian rhythm (periods longer than 24 hours) and ultradian rhythm (shorter than 24 hours).

How It Works

At the core of circadian rhythm regulation is the suprachiasmatic nucleus (SCN) in the brain’s hypothalamus. Often referred to as the body’s “master clock,” the SCN receives information about light exposure from the eyes’ optic nerves. This information helps synchronize the body’s internal clock with the external environment.

The SCN lies deep within your brain and is the master control center for your circadian rhythm. It receives light signals from your eyes, interpreting them as day or night. Based on this information, the SCN regulates the production of melatonin, a hormone that signals sleepiness.

During darkness, melatonin production increases, promoting sleep. Conversely, with light exposure, melatonin production decreases, making you feel alert.

Additionally, various genes and proteins play a role in the regulation of circadian rhythms at the cellular level.

Other environmental factors that influence circadian rhythm include:

• Stress
• Diet
• Exercise
• Daily routines
• Social interactions
• Hormones, such as melatonin, cortisol, vasopressin, acetylcholine, insulin and leptin
• Age

Circadian Rhythms and Sleep

One of the most well-known aspects of circadian rhythm is its influence on sleep patterns.

As daylight fades, the body produces melatonin, a hormone that promotes drowsiness and helps regulate sleep. Conversely, exposure to artificial light, particularly blue light from electronic devices, can disrupt melatonin production and interfere with sleep onset.

A well-functioning circadian rhythm is crucial for healthy sleep. When your internal clock is in sync with the external light-dark cycle, you naturally feel tired at night and wake up refreshed in the morning.

However, disruptions to your circadian rhythm can significantly impact sleep quality.

What Affects It?

Several factors can influence circadian rhythm, including:

• Light exposure: Irregular light patterns, like working night shifts or excessive screen time before bed, can confuse your internal clock. Exposure to natural light during the day and minimizing exposure to artificial light at night can help maintain a healthy circadian rhythm.
• Travel: Jet lag disrupts your circadian rhythm due to the rapid change in time zones.
• Sleep schedule: Inconsistent sleep and wake times can throw your internal clock off balance. Consistency in sleep-wake times, even on weekends, can support a stable circadian rhythm.
• Diet and exercise: Irregular eating habits can indirectly affect your circadian rhythm. Regular meals and physical activity can help regulate circadian rhythms.
• Shift work: Irregular work schedules can disrupt circadian rhythms, leading to sleep disturbances and fatigue.
• Age: As we age, our circadian rhythms naturally weaken, leading to potential sleep disturbances.

Other issues that can affect your internal clock include certain medications, stress, mental health conditions, brain damage and head injuries, dementia, blindness, etc.

Disruptions and Sleep Disorders

Disruptions to your circadian rhythm can be a sign of circadian rhythm sleep disorder, which manifests in various sleep disorders, including:

• Delayed Sleep Phase Syndrome: A condition where the sleep-wake cycle is delayed compared to conventional bedtime hours, aka difficulty falling asleep and waking up at desired times. People with this condition are often called “night owls.”
• Advanced Sleep Phase Syndrome: Characterized by early sleep onset and early morning wake times.
• Non-24-Hour Sleep-Wake Disorder: Disrupted sleep-wake cycle that doesn’t align with a 24-hour day, often seen in people who are blind.
• Insomnia: Difficulty falling asleep or staying asleep.
• Shift Work Sleep Disorder: Occurs in individuals who work non-traditional hours, leading to difficulties sleeping during the day and staying awake at night.
• Irregular Sleep-Wake Rhythm Disorder: When sleep is not regulated by circadian rhythm. People who suffer with this often sleep in short intervals throughout the day with no clear pattern for sleep.

How to Reset/Maintain a Healthy Circadian Rhythm

The good news is you can influence your circadian rhythm and promote healthy sleep patterns. Here are some tips:

1. Maintain a consistent sleep schedule

Go to bed and wake up at the same time each day, even on weekends, and avoid napping late in the day.

2. Optimize light exposure

Get regular morning sunlight, and avoid bright screens before bed.

3. Limit artificial light exposure

Use blue light glasses and filters on electronic devices, and dim lights in the evening to signal to your body that it’s time to wind down.

4. Regulate mealtimes

Eat at consistent times throughout the day.

5. Create a relaxing bedtime routine

Wind down before bed with calming activities like reading, listening to soothing music or taking a bath.

6. Regular exercise

Physical activity during the day can promote better sleep quality at night, but avoid strenuous activity close to bedtime.

How Circadian Rhythms Affect Health

Beyond sleep, circadian rhythm influences various aspects of health, including:

• Mood Regulation: Disruptions to circadian rhythm have been linked to mood disorders, such as depression and bipolar disorder.
• Metabolic Health: Irregular sleep patterns may increase the risk of obesity, type 2 diabetes and cardiovascular disease.
• Immune Function: Circadian rhythms play a role in regulating immune system function, affecting susceptibility to infections and inflammatory conditions.

As you can see, a healthy circadian rhythm is essential for overall well-being.

Meanwhile, disruptions can lead to various health problems, including:

• increased risk of heart disease, diabetes and obesity
• weakened immune system
• mood swings and depression
• cognitive decline and memory issues
• fatigue
• slower wound healing
• changes to the hormone cycle that could impact fertility
• gastrointestinal issues
• shifts in body temperature

When to See a Doctor

If you’re consistently experiencing sleep disturbances, excessive daytime sleepiness or other symptoms of circadian rhythm disruptions — particularly if you are practicing good sleep hygiene but still dealing with sleep deprivation — it’s essential to seek medical attention. Your doctor can help identify any underlying circadian rhythm disorders and recommend treatment options.

In addition, a health care provider can evaluate your symptoms, conduct diagnostic tests if necessary, and recommend appropriate treatments or lifestyle modifications to improve your sleep and overall well-being.

Conclusion

• Circadian rhythm is a fundamental aspect of human biology that influences sleep, mood, metabolism and immune function.
• By understanding how circadian rhythms work and implementing strategies to support a healthy sleep-wake cycle, you can optimize your physical and mental health.
• Remember to prioritize consistent sleep habits, minimize exposure to artificial light at night and seek professional help if you’re experiencing persistent sleep problems.
• With a little effort and attention, you can synchronize your body’s internal clock and enjoy the benefits of restorative sleep.
• Understanding your circadian rhythm empowers you to optimize your sleep and overall health. By incorporating these tips into your daily routine, you can strengthen your internal clock and experience the numerous benefits of a healthy sleep-wake cycle.