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Skip to 0 minutes and 7 secondsWe all do it, and we all have some idea of what sleep is. But what is the actual definition of sleep? And as scientists, how do we describe what sleep is? Well, sleep is a natural, periodically recurring state of reduced activity that is characterized by a reduction in consciousness and is also associated with decreased responsiveness to external stimuli, such as noise, as well as typical postures and behavioral changes, such as lying down and having our eyes closed. It is also characterized by a number of specific changes in physiology, particularly in relation to brain activity, as well as heart rate, breathing, and body temperature.

Skip to 0 minutes and 46 secondsIn fact, although many people may think that a sleeping person is inactive and that sleep is a reduced period of activity, some functions of the brain are actually more active when we are asleep than when we are awake. Despite these well-characterized changes that occur during sleep, the actual function of sleep has remained largely elusive to scientists, although these physiological changes do give us many hints for the reasons behind why we sleep. A large part of our understanding actually comes from what happens when we don't sleep.

Skip to 1 minute and 21 secondsSo, while we may not know the exact functions of sleep, we certainly know that without it we simply do not function, making sleep an essential aspect of our daily lives that plays an incredibly important role in our overall health and well-being.

What is sleep?

We spend a third of our lives sleeping and we know that it is a fundamental component of our health, but what is it?

In this video we begin to unpack this question and consider a few interesting facts about sleep.

Did you know?

  • Some functions of the brain and body are actually more active when we are asleep than when we are awake!
  • A large part of our understanding about the function of sleep comes from our understanding of what happens to us when we don’t sleep.
  • When we sleep, we experience changes to our brain activity, heart rate, breathing, and body temperature.

How would you answer?

  • How would you explain to a child what sleep is?
  • Do you have an interesting fact about sleep that you would like to share?

Share this video:

This video is from the free online course:

Preventing Childhood Obesity: an Early Start to Healthy Living

University of Wollongong