Circadian Rhythm: what is it?

Circadian rhythms are internal processes naturally occurring in our body. They are tied to our body clock and therefore they repeat roughly every 24 hours. These natural processes affect most living things and mainly respond to light and dark. There are many different circadian rhythms in our body such as the sleep-wake cycle, body temperature cycle, and cycles in which hormones are secreted, for example the menstrual cycle for women. Our brain receives signals based on the surrounding environment and activates certain hormones, altering our body temperature, regulating our metabolism to keep us awake or send us to sleep. Sleep is a vital activity that everyone needs to function properly. Lack of sleep or poor sleep patterns can have a detrimental effect on our health and on our daily functions. Memory consolidation, metabolic regulation and body healing take place during the sleep cycle. Hence why the sleep-wake cycle can really have an impact on eating habits, digestion, body temperature, hormone release and body functions in general. Poor sleep can negatively affect a person’s ability to function and can lead to many disorders such as diabetes, obesity, depression, bipolar disorder, seasonal affective disorder and so on.

How it works:

First, the eyes capture changes in light and dark and send signals to different cells in our brain about when it’s time to sleep or wake, or when it’s time to be more alert or more relaxed. The hormones Cortisol and Melatonin play a key role as a part of the circadian rhythm. Cortisol is produced more in the morning, and it will help us stay more alert and awake, whereas melatonin is mainly released at night, and it helps us shut us down when it’s time to sleep. Other factors that can affect your circadian rhythm are body temperature and metabolism. Body temperature drops when we sleep and rises when we wake up; metabolism works at different rates throughout the day depending on food intake and physical activity. Age is also an important factor. It’s interesting to know that newborn babies do not have a circadian rhythm until they are a few months old, which is why their sleep patterns can be irregular in the first few weeks or months. Babies start releasing cortisol from 2 to 9 months old and melatonin from about 3 months old. We see a more regular sleep pattern in children and toddlers, they in fact need roughly 9-10 hours sleep a night with early bedtime. In teenagers, the circadian rhythm changes again, although the number of hours they need remains 9-10 hours, we see a shift in bedtime, with a delayed sleep phase, helping to explain why teenagers only seem to get tired much later at night. In adults, circadian rhythm should be fairly stable. Sleep and wake times are usually consistent if we follow a fairly regular schedule and aim for 7-9 hours of sleep every night. We tend to hit our most tired phases of the day from 2 to 4am and 1 to 3pm. Circadian rhythm changes again as we age, with older people typically going to bed earlier than they used to and waking up around sunrise.

To maintain a balanced circadian rhythm, try to maintain a consistent sleep schedule. Get outside first thing in the morning, if possible, maybe sip your coffee on your porch, skip your afternoon nap and try to move more instead. Try to avoid heavy meals later in the day and give your digestive system 12 hours rest between dinner and breakfast and limit your screen time in the evenings.