What is the Circadian Rhythm?
The circadian rhythm is an internal clock within the brain, which synchronises with the body's environment to trigger when it's time to sleep and when it's time to wake up.
This biological system responds to changes in light because the body is pre-programmed to align its activity with that of the sun. Think back to a time when there was no artificial light - humans would wake at sunrise and retire when it got dark because they were no longer able to hunt, forage or perform any practical tasks. Things have moved on since then, but daylight and darkness still play key roles in regulating the body's temperature, metabolism and the release of hormones.
The circadian rhythm is run by the part of the brain known as the hypothalamus. This region is responsible for maintaining the body's homeostasis, or internal balance.
Waking up in the morning
In order to wake the body in the morning, the eye's optic nerve sends a signal to the hypothalamus as soon as it senses light, triggering a 'time to get up' morning sequence. The hypothalamus sends a message to raise the body's temperature, raise the heart rate and blood pressure and stops the brain from producing the sleepy chemical, melatonin. The body enters a more conscious state, with memory, concentration and alertness coming back to life. Sleep has now ended - Good morning.
Preparing for sleep
When it starts to get dark at night, the hypothalamus picks up on the decreasing natural light and sends out a different set of instructions. It tells the body it feels sleepy, signalling for its core temperature to drop and the release of melatonin. Drowsiness begins, the body starts to relax and prepares for sleep.
What disrupts circadian rhythm?
With busy lives and inconsistent schedules, many of us stay up late - later than the natural time the body prepares for sleep. We're surrounded by artificial lighting, smartphones, TVs and laptops, all beaming their stimulating glow in our faces.
The biological systems that regulate sleep end up out of sync, which has a knock-on effect, health-wise, as the body is unable to fulfil its night-time duties effectively. This commonly results in an inability to sleep, trouble staying asleep and frequent waking during the night.
How can we aid sleep?
There are wonder nutrients, such as Magnesium that work to relax the body and increase sleep quality. Breaking bad bedtime habits, such as scrolling on your phone right before bed, and sticking to a consistent bedtime/wake time as much as possible are also positive ways to encourage restful sleep.