People have long been fascinated with sleepwalkers — by those who roam during the night without awareness, climbing out of windows, walking down the street, urinating in a cupboard, or moving furniture.
Sleepwalking is one of a number of behaviours that can occur during deep sleep, know as the “non-rapid eye movement” (non-REM) period of sleep.
Others may include talking, sitting up, or just making odd body movements.
It’s a relatively common sleep phenomenon with an estimated 7 per cent of people sleepwalking at some time during their lives.
Sleepwalking isn’t necessarily considered a sleep disorder, unless it occurs repeatedly, includes amnesia (that is they have no memory of sleepwalking or what they did while sleepwalking), and causes distress or impairment.
Sleepwalking seems to be more common in children, with estimates about 5 per cent of children have sleepwalked at least once in the previous 12 months compared with 1.5 per cent of adults.
The decrease in observed sleepwalking is not well understood, but may be the result of brain maturation, decreased non-REM sleep as we get older and hence fewer opportunities to sleepwalk, or adults being less likely to be observed sleepwalking than younger children.
It is not yet known why some people sleepwalk and others don’t.
How does it happen?
Sleepwalking happens when some parts of our brain, particularly the limbic system (responsible for emotions) and the motor cortex (responsible for complex motor movements) are awake, while the rest of the brain is asleep.
The underlying cause of sleepwalking is not known. Sleepwalkers have their eyes open, but are relatively unresponsive to what is going on around them.
They perceive the environment differently and don’t recognise people they know.
For most people, sleepwalking doesn’t cause any problems and sleepwalkers often consider it an interesting quirk.
However, some people may suffer injuries while sleepwalking, from falls or bumping into things.
Children who frequently sleepwalk may be worried about going on school camps or sleepovers for fear of sleepwalking. Adults may forgo travelling.
On rare occasions, sleepwalkers have been violent towards others, thinking they were responding to someone threatening.
Some sleepwalkers have also sexually assaulted someone else during sleepwalking, known as sexsomnia.
On very rare occasions, sleepwalkers have died while sleepwalking and have killed other people.
In research we conducted that’s yet to be published, violence during sleepwalking is mediated by biological, psychological and social risk factors that affect impulse control.
Does anything need to be done?
If you or someone in your family is a sleepwalker, there are some things you can do to help minimise the risk of injury, including keeping furniture in the same place and not having things left on the floor that could be a tripping hazard.
Deadlocks on doors and windows can help prevent sleepwalkers from wandering outside, but it is important to ensure they can escape in case of a fire.
Sleepwalkers who are violent can minimise harm to themselves and others by removing objects that could be potential weapons from bedside tables.
It was once thought you shouldn’t wake a sleepwalker because it could harm them — there is no evidence for this.
But because they are in the deepest stage of sleep, they will be confused if woken.
While sleepwalking doesn’t normally cause daytime tiredness, most likely because the sleepwalker is still asleep, waking the sleepwalker may disrupt their sleep, which in turn may affect how they feel in the morning.
If someone in your home is sleepwalking, it is best to just tell them to go back to bed, or gently lead them to their room.
To date, there have been no clinical trials evaluating the effectiveness of treatments for sleepwalking, though myriad psychological and pharmacological treatments have been used.
If parents are concerned about their child sleepwalking, one of the most promising treatments that doesn’t have side-effects, is scheduled waking.
This involves waking the child about 20 minutes before they normally sleepwalk.
Once they are awake, you let them go back to sleep. This should be continued nightly for about three weeks. For older children and adults, hypnosis may be effective.
Adults without a history of sleepwalking in childhood, seldom start in adulthood.
If that occurs it’s best to have it checked out by a medical practitioner as it could be caused by medication or a neurological problem.
Dr Helen Stallman is a clinical psychologist and senior lecturer at the University of South Australia.
Originally published in The Conversation