Arousal During the Stages of Sleep

Arousal during sleep is caused by a change in the pattern of brain wave activity, as measured by an EEG. Arousal typically represents a shift from deep sleep to light sleep or from sleep to wakefulness.

A man sleeping peacefully in his bed
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What Is Arousal?

As it sounds, arousal is when a person becomes ‘aroused’ or more alert to some extent during the sleep cycle. It is a change in brain wave activity.

It does not necessarily mean waking up, but could just mean a shift out of extremely deep sleep to lighter sleep, from which it is easier to be woken up from.

Change in Brain Wave Activity

You might notice arousal during sleep. It is also measured by brainwave activity. Brain waves can be utilized to assess the level of consciousness or sleep stage of an individual, and thus can be used to measure arousal.

A brainwave is the summation of the electrical activity of numerous neurons. Brain waves are typically recorded by an EEG, or electroencephalogram test.

Arousal Signifies Changes in the State of Sleep

Arousal typically represents a shift in sleep states. Arousal can be a shift from deep to light sleep, or from sleep to a state of being awake.

Sleep occurs in two basic states throughout the night. The two stages of sleep are rapid eye movement sleep (REM) and nonrapid eye movement sleep (NREM). Normally, you have several cycles of these stages throughout a typical night of sleep.

  • REM is a deep stage of sleep with intense brain activity in the forebrain and midbrain. It is characterized by dreaming and the absence of motor function, with the exception of the eye muscles and the diaphragm. It occurs cyclically several times during sleep, but it comprises the smallest portion of the sleep cycle.
  • The other basic state of sleep is nonrapid eye movement (NREM) sleep. Arousal occurs more often during states of NREM sleep, which consists of three separate stages. The three stages are N1, N2, and N3, and each separate state has unique, distinct, and recognizable electrical brain wave patterns. Stage 3 (N3) of NREM sleep is the deepest stage of sleep.

Arousal can occur during any stage, and it is more common between stages

What Can You Do About Arousal?

Arousal is not uncommon during sleep, but most people fall asleep within a few minutes and don't remember it. Arousal, when you're trying to sleep, can become an issue if it occurs frequently. It can prevent some people from getting a solid night's sleep, and also from getting enough deep sleep.

One important thing to keep in mind is that it is helpful not to worry about arousal. Keep in mind that it's normal, and stressing out about it can make it worse.

Some ways to avoid prolonged arousal when you're trying to sleep include:

  • Avoid caffeine for at least 8 hours before your bedtime.
  • Keep yourself comfortable when you want to sleep by adjusting the light, noise, temperature, sleeping clothes, and blankets.
  • Exercise is often suggested as a method to help eliminate excessive sleep arousal. Exercising during the day can tire out the body, and prepare it for a solid night's sleep, making you more likely to sleep through the night.

If you are having persistent trouble sleeping, talk to your doctor. You might need a medical evaluation and treatment to help you sleep better.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Scammell TE, Arrigoni E, Lipton JO. Neural Circuitry of Wakefulness and Sleep. Neuron. 2017;93(4):747-765. doi:10.1016/j.neuron.2017.01.014

  2. Herrmann CS, Strüber D, Helfrich RF, Engel AK. EEG oscillations: From correlation to causality. Int J Psychophysiol. 2016;103:12-21. doi:10.1016/j.ijpsycho.2015.02.003

  3. National Institute of Neurological Disorders and Stroke. Brain Basics: Understanding Sleep.

  4. Passos GS, Poyares DL, Santana MG, Tufik S, Mello MT. Is exercise an alternative treatment for chronic insomnia?. Clinics (Sao Paulo). 2012;67(6):653-60.

Additional Reading

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.