“Sleep results from a complex cascade of hormones in the brain which initiate and maintain the state of sleep throughout the night”

One of the main hormones involved in sleep is melatonin.

Melatonin helps to regulate the timing of sleep onset but does not generate sleep by itself. Once sleep is achieved melatonin slowly decreases over the night and as sunlight enters the brain (through closed eyelids) the release of melatonin is stopped by the pineal gland.

As darkness falls at the end of the day the pineal gland no longer stops the release of melatonin and so the brain/body is primed for sleep again.

This is our circadian rhythm – the term for the body’s natural cycling of hormones – and simply put is the sleep/wake cycle. See https://www.sleepfoundation.org/articles/what-circadian-rhythm

Thus light (natural and artificial) is the biggest external control of our circadian rhythm. Other influences on our circadian rhythm are sound, meal timings, temperature and social cues – ie work/school timings.

Another important chemical involved in sleep is adenosine.

Another important chemical involved in sleep is adenosine. This builds up naturally throughout the day as a byproduct of using up our internal energy stores. For most people it creates an irresistible desire for sleep after 12-16 hours of wakefulness. This appears to be mainly related for a desire for deep sleep rather than REM sleep.

Luke Mastin (2017) describes this in much more detail in his blog https://www.howsleepworks.com/how_homeostasis.html

The combination of melatonin and adensosine creates the natural peaks and troughs of wakefulness throughout the day.

These are much more noticeable in people who are not achieving enough sleep at night. Caffeine temporarily blocks the affect of adenosine creating a boost when tired. This is useful just after lunch but not at 9 pm for example.

Temperature and sleep

Core body temperature also operates on a 24 hour rhythm. A 2 degree drop in body temperature helps initiate the sleep process. This is why vigorous exercise too close to bedtime wakes us up. It also explains why factors such as stress, which increases the ‘flight or fight’ response, therefore raising body temperature affects sleep. Likewise the temperature surges associated with the menopause has a detrimental affect on sleep.

Groggy in the mornings?

Sleep inertia which is the feeling of grogginess in the first 30 minutes after your alarm goes off in the morning. This is more likely to occur if you are wakened from the short period of deep sleep occurring after around 6 hours of sleep. See previous blog https://www.goodnightsolutions.co.uk/need-to-know-about-your-childs-sleep

Quick recap!

Regular sleep and wake times to help our circadian rhythm. Cool and dark bedrooms help the hormone cascade initiate sleep. Try to reduce worries and anxieties which can affect sleep. Prioritise as much sleep as possible to reduce sleep inertia and sleep deprivation.

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