Sleepwalking, also called somnambulism, is when someone moves around during sleep, carrying out complex activities. These can range from the relatively harmless, such as walking round a room, to the potentially dangerous, such as trying to light a fire. Perhaps fortunately, most sleepwalking activities are not done well.

What are the characteristics of sleepwalking?

Sleepwalking tends to occur in the first one to three hours of sleep, and is most common in children. An individual sleepwalk can last only a couple of minutes or it can extend to half an hour. Someone who is sleepwalking can appear awake as their eyes are open, but they have a glazed expression and appear not to notice their real surroundings.

Sleepwalking can be limited to just walking in the bedroom, but in severe cases children and adults may move around the house, or even try to leave the house. This is obviously dangerous and parents with a child prone to sleepwalking need to take care to make this impossible.  Usually, sleepwalkers have no memory of their nightly walks.

Sleepwalking and the sleep cycle

The term sleep cycle describes the different types of sleep you pass through each night. Sleep consists of rapid eye movement (REM) sleep and non-REM (NREM) sleep. We normally dream during REM sleep but not NREM sleep. NREM sleep is sub-divided into four sub-stages, N1–N4 which you pass through before entering REM sleep. In most people, the cycle of N1-N4 sleep plus REM sleep lasts about an hour and a half, so it’s usual to go through about five cycles per night.

Sleepwalking tends to occur only in the first or second cycle, and within each cycle it tends to occur within the N3 or N4 sub-stages.
Is sleepwalking common?

Sleepwalking may affect up to 15% of the population, but is most common in children aged four to eight years old. It tends to be more frequent and to last longer, however, when it occurs in adults.

What are the causes of sleepwalking?

Several causes have been identified:

  • Genetic: sleepwalking tends to run in families so genetic factors are implicated but not fully understood.
  • Lifestyle: relevant factors include sleep deprivation, alcohol abuse, disrupted sleep patterns (jet lag for example), stress and drug abuse. All may increase the risk of sleep walking.
  • Medication use: any medication that can affect sleep may also increase the risk of sleepwalking. Such medication includes hypnotics (drugs that make you sleepy); neuroleptics (drugs that treat epilepsy or mental illness); stimulants (such as caffeine and alcohol) and antihistamines (such as anti-allergy medication).
  • Pregnancy and menstruation increase risk of sleepwalking in some women.

Conditions associated with sleepwalking

Many medical conditions are associated with sleepwalking, to a greater or lesser degree. These include abnormal heart rhythms, asthma, fever, panic attacks, post-traumatic stress disorder, sleep apnoea (difficulty breathing when asleep) and gastroesophageal reflux (regurgitating food into the oesophagus).

Conditions that tend to occur with sleepwalking more frequently include:

  • Narcolepsy: this is a condition in which people fall asleep uncontrollably during the day, but have difficulty sleeping at night. Narcolepsy can be similar to sleepwalking in that narcoleptics may ‘sleepwalk’ when catnapping. Narcolepsy is a more serious problem than sleepwalking, however, and is characterised by an abnormal sleep cycle. ‘True sleepwalkers’ rarely move around when catnapping.
  • Automatism: this is unconsciously performing routine activities over and over again. It occurs in sleepwalking, but is not peculiar to it. It may also occur in narcolepsy and in some forms of epileptic fit.
  • Night terrors: these cause extreme fear accompanied by a very rapid pulse rate, sweating, screaming and thrashing. Like sleepwalking, a night terror tends to occur in the NREM stages of sleep but unlike sleepwalking, it is a horrific experience.
  • Sleep-talking: this often occurs with sleepwalking. Often, the sleep-talking is incomprehensible or makes no sense. Sleep-talking may occur independently of other physical activity.
  • Nocturnal enuresis: bed-wetting is common in children who sleepwalk.

What do I do if my child sleepwalks?

Sleepwalking in children does not usually indicate an underlying serious problem, and is usually temporary. The main danger is from falling over or banging into things, or opening a door to the outside. So, if your child sleepwalks, remove potentially dangerous objects from the child’s bedroom and make sure they are unable to leave the house when they sleepwalk.

Making sure your child has good sleep habits can also help. Set up regular bedtimes, regular getting up times, and do not allow them to watch television in bed. Regular physical activity, especially outside in sunlight, is also important, as is a good diet. It may also help to check for other lifestyle factors, such as stress at school.

If the sleepwalking continues, consult your GP for advice; he or she may prescribe treatment similar to that for adult sleepwalkers, but this is less likely to involve medication.