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How does the brain know to sleep?

Updated: Apr 30

Sleep is something that the body requires. How many hours you sleep may vary but how does the brain know to sleep? In a previous post, we talked about melatonin levels and circadian rhythms. But did you know that we have a 'homeostatic sleep drive'?

What is a sleep drive?

A homeostatic sleep is a mechanism to 'fall asleep' and on the other end of is the 'awake drive'. The 'sleep drive' is influenced by the number of hours we have been awake, our environment, circadian rhythms and the neurotransmitter hormone adenosine.

We have receptors for this hormone and when we are awake our bodies create an increase of this hormone. Then when we sleep there is a decrease the in hormone level.

According to a 'Health Sleep' Harvard education article, during your initial 'slip into slumber' the balance of the 'sleep' and 'awake drives' are declining and rising. After the first 4 hours of unbroken sleep the body then relies on the circadian rhythm - its own internal time keeper - to sustain us in sleep. This is further supported by the vagus nerve, which works with our parasympathetic nervous system to promote a relaxation response, helping us to stay asleep.


Insomnia is defined as the inability to fall asleep or stay asleep. It can cause you to wake up too early and not be able to get back to sleep. The statistics on sleep by Formulate Health (now CyberCrew) in March 2021 state that 36% of adults in the UK have problems falling asleep on a weekly basis and at least 50% on a monthly basis. They also state that women are more prone to this than men and the age range 45-54 struggle the most. In women this age range is also a time when hormones are fluctuating, perimenopause and menopause.

Balance and Consistency

Our bodies are always working to bring us back to homeostasis and our lifestyles, habits and environment all influence the ability of our bodies to support us with ease, or not. Taking the time to understand more about your own body and what works for your is important. The more awareness you bring to yourself and the subtle ways that your body communicates to you, the more opportunity you have to create routines and habits that help you thrive.

What actions can you take today to become more aware of your lifestyle and make changes to promote healthy sleep habits and routines for yourself?


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