A circadian rhythm is a 24 hour cycle that your body’s internal clock follows. It is affected by many different influences, including:
The circadian rhythm is controlled by a ‘master clock‘ (or pacemaker) in the brain that coordinates your mental and physical processes. This master clock is connected to other peripheral body clocks located throughout different organs that must all be in sync in order to have a healthy circadian rhythm.
Just to be clear, sleep and circadian rhythm are biologically different, but are very closely intertwined. The master clock is particularly sensitive to light, which is why circadian rhythms typically revolve around night and day (sleep and wake.)
We all have a natural propensity to a certain circadian rhythm. These are called chronotypes, of which there are four:
A messed up circadian rhythm can have a detrimental effect on your quality of life.
Disrupted or poor circadian rhythm has a proven association with bowel problems such as IBS and colorectal cancer. Intestinal cells have their own circadian rhythm that influences gut motility (the movement of food through the digestive tract.) It’s important for the sake of digestion that food efficiently move through your system. When the transit of food is interrupted, it can result in symptoms like GERD, gas, constipation, stomach pain, diarrhea, and more severe problems such as IBS, diabetes, and nutrient malabsorption.
What comes first, the chicken or the egg? Stress has a cause and effect relationship with the circadian rhythm, meaning stress can both disrupt the circadian rhythm, as well as be be the result of a disrupted circadian rhythm.
Stress that can be found in our day-to-day, defined as excessive psychological or physiological demand, can impact our sleeping patterns by interfering with the regulation of the stress response (cortisol production.) Being in a heightened state of stress delays the time it takes to fall asleep by increasing the heart rate and inducing rapid, anxious thoughts at night.
The majority of us live on schedules dictated by our jobs and commitments, which more often then not require rigid wake up times. When the onset of sleep is delayed at night, total sleep time is reduced, and the snowball effect continues.
The effects of lost sleep time due to stress include impaired memory and mood regulation, which often leads to more stress, therefore more impact on sleep, and more disturbed circadian rhythm.
A disturbed circadian rhythm can have a devastating impact on the immune response, resulting in inflammation and a state of immunocompromise which makes us more susceptible to disease.
Inadequate sleep (less than 6 hours) has a negative effect on the immune system’s response to vaccination as well. Studies show that sleep deprivation prior to vaccination reduces the affect of the influenza vaccine.
Total sleep deprivation is actually deadly, and studies point to immune dysfunction due to lack of sleep as being a potential culprit.
Unsurprisingly, many mood and mental health disorders can be caused or exacerbated by a disturbed circadian rhythm.
Most of the studies regarding circadian rhythm and mood disorders follow the sleep patterns of night-shift workers, who are 40% more likely to develop depression.
Depression itself might also have its own circadian rhythm, as symptoms (fatigue, anger, sadness, brain fog) are often worse in the morning.
This review cites considerable evidence that there is a link between disturbed circadian rhythm and depression. Many theories exist as to why this is the case, but they all revolve around a common theme of a mismatch between the sleep cycle and circadian rhythm which then throws off the ‘master pacemaker’, resulting in misregulation of body temperature, cortisol, melatonin, and REM sleep.
A similar correlation exists for anxiety. A disrupted circadian rhythm has been found to increase symptoms of anxiety, with a potential that sleep treatment could treat an array of mental health diorders.
“They also suggest that sleep-focused therapies, such as treatments to regulate circadian rhythms, may be beneficial in the prevention or treatment of a vast array of diseases, including Alzheimer’s disease and anxiety disorder and furthermore emphasize the critical need of good sleep for everyone’s health.”
– Clifford Saper, MD, PhD, Harvard Medical School
A correlation has also been found between people who are naturally ‘night owls’, and an increase in occurrences of anxiety. This study revealed that students whose natural chronotype favours the night time showed more anxiety than student who are naturally early risers.
To get the maximum benefit, you can either adjust your lifestyle to match your circadian rhythm, or vice-versa.
Possibly the most important tip for optimizing your circadian rhythm is to go to sleep and wake up at the same time each cycle. By doing so, you’re literally conditioning your body to follow and get comfortable with this cycle.
Bright light exposure, especially in the morning, promotes wakefulness. Best case scenario is natural sunlight, but artificial light works well too. Turn on as many lights as you can first thing in the morning.
Similarly, try to limit your light exposure at night before bed (especially blue light from screens!) which inhibit melatonin production.
Make yourself a pre-bedtime routine that involves calm, quiet activities such as stretching, meditation, or reading.
Setting your meals at similar times each day also acts as a way to train your body clock, especially when done at the same time each morning.
Napping during the day makes it more difficult to fall asleep at night. Rather push until the evening and have an early night.
The ideal environment for sleep is a cool, dark, quiet room. With regards to temperature, 65 degrees Fahrenheit (18 celsius) is a good temperature to aim for, but ultimately you should set the thermostat at whatever’s most comfortable.