Fine-tune your circadian rhythm

We’ve all heard of circadian rhythms. At a very basic level they regulate our cycles of sleep and wakefulness. Beyond this, they influence many other cyclical processes related to regulating body temperature, blood pressure, heart rate, metabolism, energy expenditure and hormonal secretions. Establishing habits and routines that align with these cycles can be a powerful way to maximize the natural rhythm of our body to support health and vitality.   

Circadian Rhythm 101

Sunlight is the most important factor influencing our circadian rhythm. At every start of the day, our hypothalamus registers the first daylight, and this activates wakefulness. Our body temperature goes up, cortisol levels rise and blood pressure increases, all to get us out of bed and start our day. Another important signal occurs when we eat for the first time: this stimulates saliva production and activates digestive function.

In the evening, as daylight wanes, the opposite needs to occur: Melatonin production increases, the GI tract slows down, our body temperature drops, and cortisol levels and blood pressure should come down, all in preparation for sleep.

What can disrupt our circadian rhythm?

When our circadian rhythm is disrupted, we might see symptoms like daytime drowsiness, sleep disturbances, decreased cognitive performance, and difficulties with learning and memory. We might struggle with irritability and anxiety, depression can feel more intense, and we might suffer from GI complaints. Beyond these noticeable symptoms, long-term chronic misalignment of our sleep-wake, and feed-fast cycles can disrupt metabolic processes and can contribute to chronic disease.

Currently the biggest disrupter of circadian rhythms comes from the blue light waves emitted by our devices. There is a light-sensing protein in the eye that resets our circadian rhythm when we are exposed to morning light, and it cannot distinguish this natural light from the blue light from our screens. Both sunlight and blue light signal the brain that it’s daytime and can disrupt our melatonin production at night.

In the past some of the most common disruptors of our circadian cycle was shift work, especially night shifts. Other big disruptors are jet lag from traveling across multiple time zones, and what is called ‘social jet lag’ which happens when we stay up late on weekends.

Tips for supporting optimal circadian rhythms

Keep to a steady sleep routine: Ideally try to sleep for 7-8 hours each night between the hours of 9pm and 8am. Try to keep a steady bedtime within about an hour range, and even on the weekends, try not to stay up too late. Apparently getting less than 7 hours of sleep per night can create a sleep debt, which we can’t necessarily make up for by sleeping in on the weekends.

Have a consistent breakfast time: Our first meal of the day gets our digestive tract working. Erratic breakfast times confuse our organs and have implications for our digestive health.

Get morning daylight: Morning sunlight is the most important reset for our circadian rhythm. And when light cues coincide with exercise, circadian rhythm alignment occurs even faster than without exercise.

Find the right time for exercise: As mentioned above, outdoor morning exercise is a great way to reset the circadian clock. Later in the afternoon between 3-6 pm, is another great time to exercise, because muscle tone rises, motor coordination, blood flow, and muscle repair all peak during that time, making it ideal for building muscle. Evening exercise, especially after dinner, is not recommended because exercise can increase cortisol levels which may affect our ability to fall asleep.

Healthy dinner time: Saliva production is circadian, and we produce up to ten times more saliva in the daytime compared to nighttime. One of the functions of saliva is to help neutralize stomach acid, so if we are eating late, while we are producing less saliva, we often end up experiencing heart burn or indigestion. Also, gut motility slows down in the evening, and it might take up to 2 hours to digest and absorb a meal, which means it is best to stop eating (and snacking) 2-3 hours before bedtime.

Be aware of stimulants: For those who are sensitive to caffeine, it is best to stop having caffeinated drinks after 12 or 1pm, to avoid it interfering with melatonin production later in the day. Evening alcohol can cause dehydration which can disrupt sleep and it is best to avoid it for 2-4 hours before bed.

Evening entertainment: Many of us spend evening hours relaxing in front of the TV or on our devices. As mentioned above the blue light from our devices can interrupt our melatonin production, making it difficult to fall asleep. It is best to avoid screen time for 1-2 hours before bed. Alternatively, consider using blue light filters on devices or wearing amber glasses to minimize the effect of blue light on the brain.

Establish a consistent bedtime routine: Sleep is a very important synchronizing signal for circadian rhythm, and the timing, quantity, and quality all matter. It is essential for our body’s ability to heal and detox, and chronic sleep disruptions can have serious health impacts. I have read that for every hour we are awake during the day, we need 20-30 min sleep at night, and that every hour we are awake past midnight, can disrupt our circadian rhythm.

I hope these ideas are helpful for fine-tuning your circadian rhythm and supporting your health.