The sun rises and the birds start to sing; plants stretch towards the sun, and people emerge from their homes to start a fresh new day. In the evening, the sky darkens and the moon rises; street lights come on, flowers close, and people retreat back into their homes to go to sleep.

In the same way that our environments abide by a daily routine of energy and rest, our bodies follow a similar cadence.

Before we wake, our body temperature rises, cortisol levels increase, digestive juices start to flow, and our muscles become primed for movement. When we go to sleep, our body temperature drops, melatonin increases, and our brain, liver and intestines initiate their self-cleaning and restorative processes.

This is called a circadian rhythm (from the Latin terms  “circa” and “diem”- literally “about a day”), and it controls the physiological processes of all living things.

While modern societies have evolved in opposition to our circadian rhythms (through night shifts, blue light and time spent indoors), recent studies suggest that our health may suffer because of it. Many chronic diseases such as sleep disorders, obesity, diabetes, depression, bipolar disorder, and seasonal affective disorder have been linked to irregular circadian rhythms.

This article shares key findings about circadian rhythms, while providing guidance on how to nurture your circadian rhythm for optimal health.

How Circadian Rhythms Work

Every single day, each one of our genes and hormones get turned on or off according to a schedule. This schedule promotes our metabolism and allows our physiological processes such as digestion, hormone release, brain activity, and more to function throughout the day.

Just like all aspects of nature, our bodies need balance. We are predisposed to spend about 12 hours every day moving, eating, thinking, and processing; while we are equally hardwired to spend 12 hours every day resting, relaxing, and repairing.

So whether you’re conscious of it or not, there is a prewritten symphony of activities happening in your body every day, and it’s informed by thousands of years of genetic code. Although we often ignore the clues to our own circadian rhythms, like sleeping when we’re tired or rising with the sun, the science suggests that this schedule is there for a reason.

Key Functions Associated With Circadian Rhythm

• Digestion
• Metabolism
• Mental Performance
• Hormone Release
• Physical Activity
• Sleep

The Impact of Sunlight on Circadian Rhythms

The one thing that plants, animals, and humans have in common when it comes to circadian rhythms is that we are all on a 24-hour cycle controlled by the sun.

We anticipate and respond to the rising of the sun through predictable biological adjustments made in our body. In the evening, complementary biological processes occur that seem to predict and respond to nightfall. Even if we are in a closed room without access to the sun, our bodies still rise and fall in these predictable patterns. This indicates the internal (or endogenous) nature of our circadian rhythms that are seemingly working in concert with external triggers, rather than just in response to them.

Modern Lifestyles & Circadian Rhythms

Pre-industrial cultures tend to be more in tune with the earth’s natural rhythms of light and darkness for practical reasons: wIthout electricity, it is difficult to perform many activities after dark.

Over the years, developments in electricity, lighting and technology have allowed us to stay up late for work and entertainment.

These days, Americans are known to spend 90% of our time indoors where we’re often exposed to blue light–– stimulating our brain and suppressing melatonin–– again, making it harder to sleep.

To make matters worse, it is increasingly common to eat late, which can further throw off our circadian rhythm. Our bodies are designed to secrete digestive juices and process food mostly during the day, so they can rest and engage in restorative practices at night.

When we don’t sleep deeply at night, organs such as our liver and brain might not be able to go through their cyclical functions of flushing toxins. This can contribute to feeling ill or cloudy-headed in the morning.

When this happens sporadically, our bodies can reset themselves without impact. However, when this behavior becomes a pattern, our bodies might be prevented from fully engaging in their vital processes, which can increase our risk for many diseases.

For instance, Shift Work Sleep Disorder (SWSD) is a condition commonly associated with nurses, security guards, and other “night shift” workers. Individuals with SWSD often have trouble sleeping, feel constant fatigue, and suffer from poor mental and physical health. Although many night shift workers take measures to create environments during the day that promote sleep (like blackout curtains, earplugs and eyeshades), their sleep can still suffer. This again is evidence of circadian rhythms dictating optimal times for sleep and wakefulness, and the limits of human intervention.

Since our bodies are still hardwired to sleep at night and wake during the day, any departure from our pre-designed schedule can disrupt our bodily processes, producing an irregular circadian rhythm which compromises our sleep and increases our risk for disease.

Circadian Rhythm Research

It is important to note that the science of circadian rhythms (also known as chronobiology) is extremely complex. It wasn’t until the mid-20th century that researchers formally observed body-clock patterns in plants, mice and other animals. Only recently has science studied the complex effects of circadian rhythms on humans.

The majority of what we know about circadian rhythms has been derived from animal studies and human epidemiological studies focused on sleep. This research hints at a massive and intricate interplay between a 24-hour schedule and our essential bodily functions.

Recently, major headway has been made in chronobiology. In 2017, a Nobel Prize was awarded to scientists for their extensive circadian rhythm research. Dr. Satchidananda Panda, a leading chronobiology researcher, works in partnership with the Salk Institute to help people understand their relationship with their own circadian rhythms.

In a breakthrough study done on mice, Panda’s lab discovered that when mice consumed calories within an 8-12 hour period during the day, they avoided high cholesterol, diabetes and obesity. However, when mice were able to eat calories at all hours of the night, their chances of high cholesterol, diabetes and obesity increased.

Along with optimal times for eating, Panda’s research highlights optimal times for exercise, mental performance, and sleep based on circadian rhythms.

Practical Tips to Nurture Your Circadian Rhythm

1. Limit Blue Light Exposure

Blue light is commonly emitted from cell phones, computers, TVs and LED lighting. Blue light has a particularly stimulating effect on our nervous system by suppressing melatonin and increasing alertness. While many of us watch TV, read on an iPad, or use our phones before bedtime, this simple behavior can have a detrimental effect on our sleep. To avoid sleep disruption from blue light, avoid screens 2 hours before bedtime and opt for a book instead.

2. Sleep in a Dark Room

Since light, in general, can stimulate feelings of wakefulness, a bright room can impede our ability to fall into a deep sleep. If street lights, city lights, or any other outside light comes through your bedroom windows, consider purchasing blackout curtains in order to have a completely dark environment to sleep in.

3. Keep Your Bedroom Around 67 Degrees

Since body temperatures drop during sleep, you can help facilitate this process by sleeping in a cooler room at night. Studies consistently show that room temperature impacts sleep quality, so making this simple change might improve your ability to have a good night’s sleep.

4. Stick to a Schedule

With travel, work, children, and social obligations, it can be difficult to stick to a regular sleep/wake schedule. However, abiding by a regular bedtime and wake up time is beneficial in nurturing your body’s circadian rhythm. By going to bed and waking up at approximately the same time every day, your body can predict, and regulate its essential processes.

5. Sleep for at Least 7 Hours Per Night

A joint consensus from the American Academy of Sleep Medicine and the Sleep Research Society agree that healthy adults require at least 7 hours of sleep per night. Many survive on less, but if you wish to nurture your circadian rhythm to promote optimal health, at least 7 is best.

Final Thoughts

Circadian rhythms are invisible, and somewhat difficult to understand. From a scientific standpoint, we are just now beginning to study this fascinating interplay of bodily processes during a 24-hour cycle. But if we take a look at the way that nature operates externally, we can intuit a sense of what may be happening internally.

Rest balances activity, and there is no way to avoid it. Both are crucial to the functioning of the whole. With this in mind, we can either tune into our circadian rhythm and work with it, or we can ignore and try to fight it. If we work with it, not only can we learn a lot about each of our unique bodies, but we can also understand how to best support our natural tendencies based on a much older and wiser genetic clock.

Want more tips on getting restful sleep? Take a look at this TelMD Upstream Blog post.

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