Sleep and the Brain

  • Published23 Jul 2015
  • Reviewed23 Jul 2015
  • Author Michael W. Richardson
  • Source BrainFacts/SfN
This chart shows the brain waves of a young adult recorded by an electroencephalogram (EEG) during a night's sleep.

Brain Activity During Sleep

Although sleep appears to be a passive and restful time, it actually involves a highly active and well-scripted interplay of brain circuits, resulting in sleep’s various stages.

Illustration by Lydia V. Kibiuk, Baltimore, MD
This chart shows the brain waves of a young adult recorded by an electroencephalogram (EEG) during a night's sleep.
Diagram of the parts of the brain directly involved with sleep

The Sleep-Wakefulness Cycle

Why do we get sleepy? There are two main determining factors: the circadian system (time of day or night) and how long we have been awake.

Illustration by Lydia V. Kibiuk, Baltimore, MD; Devon Stuart, Harrisburg, PA
Diagram of the parts of the brain directly involved with sleep
Whole-mount X-gal staining of sensory axons innervating the limbs of an embryonic day 15.5 mouse carrying the LacZ gene driven by the sensory neuron promoter of Brn3a.

How Is Sleep Regulated?

What is the difference between sleep and wakefulness? Much of it depends on which brain systems are activated.

Schoenmann, et al. The Journal of Neuroscience, 2010.
Whole-mount X-gal staining of sensory axons innervating the limbs of an embryonic day 15.5 mouse carrying the LacZ gene driven by the sensory neuron promoter of Brn3a.
Man taking a nap

What happens to your brain when you are sleep-deprived?

Although scientists continue to debate the purposes and benefits of sleep, one thing is clear: sleep deprivation is really bad for brain function.

Courtesy, with permission: epSos.de
Man taking a nap
Painting by William Powell Frith, "Sleep" - 1873.

The Secret to Memory? A Good Night’s Sleep

A good night’s sleep can strengthen memories and promote creative thinking.

William Powell Frith
Painting by William Powell Frith, "Sleep" - 1873.
Illustration of man sitting on bed looking at his smartphone.

How Smartphones Keep You Awake

Your smartphone addiction isn't helping you sleep. In fact, an obscure chemical reaction may be keeping you awake.

Illustration of man sitting on bed looking at his smartphone.

You likely spend more of your life sleeping than performing any other activity, but there’s so much we don’t know this basic function. Scientists continue to make discoveries about the role sleep plays in our ability to think, remember and act.  To find out more about sleep and the brain, browse through the images and their descriptions and click on the link in each caption to read the full articles.

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