What is sleep

At its most basic, sleep is a biological process that plays a vital role in physical health and wellbeing. Sleep is part of everyone’s life. Sleep allows our bodies to carry out functions that are vital for our physical and mental wellbeing, leading to a whole range of benefits.


Why do we sleep?

We still don’t really know, but we do know that we need it. Eventually, no matter how hard we fight it, we will want to sleep for at least part of every 24 hours.


What causes us to sleep?

Circadian rhythm

 Also known as our body clock. This runs on an approximately 24-hour cycle.

Many biological functions have a rhythmic cycle: Sleep/Wake, Body Temperature, Hormone release (Melatonin, Cortisol, Growth hormone)

Our body clock is affected by what are known as Timegivers. These are elements in our environment that provides the stimulus to set or reset our body clock. Examples of Timegivers include light, meal times, social activity, and exercise.

Sleep drive

 Also known as sleep pressure.

This is the process that makes us feel sleepy. The longer we go without good quality sleep, the higher our sleep drive. We can support our sleep drive being at its peak at bedtime by getting plenty of exercise and activity during the day, and avoiding naps.


These 2 processes interact with each other – the circadian rhythm influences how sleepy a sleep-deprived individual feels.

The way our body clock works affects how tired we feel when we don’t get enough sleep. If we don’t sleep all night, we might feel okay in the morning because our body clock makes us less sleepy. But later in the day, our body clock and the fact that we haven’t slept enough can make us really want to sleep.


Night Owl or Morning Lark

Knowing where your own body clock naturally sits within a 24-hour period can make a difference when trying to get a good night’s sleep. Some of us naturally have a lot of energy first thing in the morning, while others come to life in the evening. And many people are somewhere in between.

It does not mean (as is often implied) that night owls are more lazy because they don’t come to life until later in the day. It all comes down to their internal body clock and their natural release of their body clock hormones, cortisol and melatonin.

Related topics

Find out more

Get in touch to find out more about the services, information and support we offer.