What are circadian rhythms?
Circadian rhythms are the daily ~24 hour cycles of your body clock. Although we often focus conversations about circadian rhythms to sleep and energy, there are actually other reasons to discuss this essential body clock. The 24 hour cycle is interwoven into a wide variety of body functions.
How does your body clock work?
Ideally, the body clock has a natural ebb and flow throughout a 24 hour period to allow for optimal energy and function throughout the day. In flowers, they assist the flower to open and close at the right times of day, and in animals they manage timing on feeding and resting cycles. On a basic level, the same is true in your body. Circadian rhythms coordinate your physical and mental systems, allowing your body to produce the proteins, enzymes, and hormones needed to meet your normal daily energy output (movement, exercise, activity) and input (sleep & food). If you want to nerd out on the anatomy, your hormone release organs are sent signals by the suprachiasmatic nucleus (SCN) located in the hypothalamus in your brain. We will call this the body clock pacemaker. Responding to external cues like daylight (melatonin) and lack of routine in your sleep schedule and internal cues like blood sugar, body temperature and stress hormone (cortisol). The SCN works to ensure that you are fueled with the right amount of energy for your waking hours and your cells and body are winding down to be ready for your sleeping hours.
How does the body clock affect sleep?
The primary concern for most of us when it comes to the body’s clock is with respect to sleep: during the day, light exposure causes the SCN to send out signals to trigger your body to be more alert. In the evening as light levels drop, your SCN sends out the trigger for your body to increase the production of melatonin, which promotes sleep, and works to keep you asleep throughout the night until light levels start to increase again. This is why sleeping in an environment with inconsistent light or too much light can impact both the quality and duration of your sleep. Circadian rhythms and sleep quality can also be impacted when you have an inconsistent sleep schedule, as with someone who works shift work or during the night. It can be difficult for someone like a nurse who works long hours during both daylight and darkness to achieve any kind of balance in their circadian rhythms.
Because the SCN affects the release of many other hormones, dysregulation of your body clock can impact basic bodily functions such as eating habits, digestion and body temperature. This is why when you have to get up earlier than usual you can feel cold, groggy, and unprepared to eat, as your SCN has not yet sent the usual signals for hunger, digestion, and a warmer waking temperature.
What can you do to help manage your body’s rhythms?
There are several ways to help manage your circadian rhythms, especially when it comes to sleep:
Be consistent in your sleep schedule: Going to bed and getting up at the same time each day helps to reinforce your natural SCN cuing and improve sleep quality. For those who have to work shift work this can be more difficult verging into impossible, but being as consistent as you can within your weekly schedule will help.
Get daily exercise: Being active during the day can help manage your energy and support better sleep at night. You may notice that being consistent with the time and intensity of your activity each day also supports improved sleep quality.
Avoid caffeine and other stimulants: You may be one of those lucky people who can drink a cup of coffee and go right to sleep, or you may be one who can’t even think about the stuff past noon if they want to sleep before midnight. If you are struggling to fall asleep, take a look at your stimulant consumption to ensure that you’re not confounding your own efforts at night.
Limit light before bed: We’ve already discussed that light levels impact your SCN and melatonin production, this is why we should try not to use our phone or tablet right before bed.
Use blackout window coverings: Try to limit how much light pollution is in your bedroom at your bedtime and during your sleep time to help improve your sleep quality and duration.
Use a bedside sunrise simulator alarm clock: These bedside lamps start to gradually turn on and increase the light as your set wake up time approaches. This acts to trick your SCN to think the sun is rising and it is time to wake up.
Bask in the sunshine: In the same way that aiming for less light before bed makes you sleepy, more light in the morning can help you feel more awake and energetic to tackle your day.