Rest, Relax and Nurture Your Biological Clock This Holiday Season

We are going into the winter months here in the northern hemisphere, and the holidays are just around the corner.

How do we best support the body during this time of the year?

One of the significant changes during fall and winter months compared to the summer is the much shorter daytime and much longer nighttime.

How does that affect the body?

The human body has a 24-hour internal biological clock, called the circadian rhythm, which synchronizes to the natural light-dark cycles.¹

The circadian rhythm is regulated by an important hormone, melatonin (also called the sleep hormone).¹

Darkness triggers the production of melatonin, which in turn promotes the onset of sleep time. On the other hand, light suppresses the production of melatonin and promotes wakefulness.^1,17

Therefore, when exposed to only natural light (i.e., without artificial lighting at night), the body’s will naturally align its wake-sleep cycles with the natural light-dark conditions.^1,17

Importance of the Circadian Rhythm

More and more scientific studies have shown that our organs and body functions work according to the circadian rhythm.

It is important to allow the body’s circadian rhythm and melatonin production to be in-sync with the natural light-dark conditions.

Many lifestyle habits in our modern living, however, can disrupt the circadian rhythm contributing to poor sleep quality and health issues.

Some examples of the lifestyle habits are listed here:^2–9

• Chronic or habitual shift in sleep-wake cycle, shift work, chronic or frequent jetlag, habitual sleeping past midnight, and irregular sleep and wake-up time (social jetlag).
• Exposure to blue light (emitted from computer, device screens and other electrical lighting) in the evening which suppresses melatonin, promotes alertness, and shifts the circadian clock to a later time. Among the different types of artificial lights, LED light is the worst, followed by fluorescent light and then incandescent light.
• Eating too close to bedtime.
• Consuming caffeinated drinks or foods late in the afternoon or evening.
• Consuming alcohol before bedtime which can increase arousal during second half of the night
• Engaging in moderate-to-high intensity physical exercise in the evening.
• Engaging in high mental intensity tasks or mentally/emotionally stressful activity in the evening.
• Exposure to electromagnetic radiation (e.g., from wireless devices, Wi-Fi etc.) prior to or during sleep, which can alter brain waves and induce cortical excitability resulting in disrupted and nonrestorative sleep.

Disruption and dysregulation of the circadian rhythm and melatonin production can increase the risks of many chronic diseases/disorders.

Such chronic diseases/disorders include all-cause mortality, overweight and obesity, diabetes, hypertension, high cholesterol, cardiovascular/heart disease, poor immune health and chronic inflammation, hormonal imbalance, cancers, gut disorders/diseases, liver disease, cognitive function and memory impairment, Alzheimer’s disease and dementia, and poor mental health, etc.^10–16

Support Your Circadian Rhythm During Wintertime

Depending on where you live, there may be a large shift in sunset and sunrise time between winter and summer.

Here in California, the sunset time in winter is about 2.5 hours earlier than that of the summer, while sunrise time in winter is about 2.5 hours later than that of the summer.

On winter solstice day (i.e., the shortest daytime of the year) which falls on December 21 this year, sunrise is at 7:14am while sunset is at 4:51pm.

When exposed to only natural light, the body’s circadian rhythm will automatically adapt and entrain to the seasonal shift in light-dark timing.¹⁷

The onset of melatonin production will occur much earlier in the evening when compared to the summer. It is therefore natural to sleep earlier and perhaps also give ourselves permission to sleep longer during wintertime.¹⁷

In general, regardless of the time of the year, we want to maintain a healthy sleep-wake cycle by going to bed well before midnight, ideally before 10-11pm, and perhaps even earlier (an hour or more earlier) during wintertime.

Additional tips to support the body’s natural circadian rhythm include:

• Maintain a regular sleep schedule.
• Minimize or reduce exposure to artificial light, especially blue light from devices and electrical lighting, by dimming light in the house and minimizing screen time in the evening.
• Establish a bedroom environment that is conducive to sleep, including sleep in a pitch-dark and quiet room, with comfortable bedding, etc.
• Eat the last meal of the day at least 3 hours before bedtime to allow active digestion to be completed before bedtime.
• Avoid caffeinated drinks or foods in late afternoon and evening.
• Avoid alcohol before bedtime.
• Avoid tobacco or nicotine containing products.
• Unwind and prepare the body to be in resting and parasympathetic mode 2-3 hours before bedtime, by avoiding moderate-to-high intensity physical activities and mentally/emotionally stressful activities, and engaging in relaxation activities (e.g., taking warm bath, listening to relaxation music, gentle yoga or stretching, meditation, etc.).
• Perform regular physical exercise during the day to help regulate circadian rhythm. Moderate-to-high intensity exercise should be performed during early part of the day.
• Get adequate exposure to natural daylight especially in the morning and midday. Unless your home or building design allows abundant daylight access, it would be better (if weather permits) to go outdoor for a walk or other outdoor activities in the morning or midday. This not only gives you natural daylight exposure (and sunlight for vitamin D), it also gets your body moving and helps to reduce stress.

For more detailed discussion and tips to promote better sleep and healthy melatonin production, please check out my previous articles: Tips for Better Sleep to Support Your Immune Health and Overall Health, Melatonin – Not Just Your Sleep Hormone.

Related Articles

Tips for Better Sleep to Support Your Immune Health and Overall Health

Melatonin – Not Just Your Sleep Hormone

References

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