A TEENAGE girl in London leaves her house and climbs to the top of a 40-metre crane. An Australian woman goes off in the middle of the night to have sex with strangers. A Canadian man drives 22 kilometres to his in-laws鈥� house, murders his mother-in-law and drives back home. Strange behaviour, but stranger still when you consider that all these people were asleep at the time.
Sleepwalking 鈥� technically, somnambulism 鈥� is the acting out of complex behaviour while sleeping. Actions can be anything from just stumbling about to driving, doing the laundry and even cooking. This year, many cases of sleep-eating have come to light as a possible side effect of the prescription sleeping pill Ambien. One 54-year-old woman had no clue why she had gained 45 kilograms until her husband and sons told her that she was climbing out of bed in the middle of the night, heading for the kitchen and bingeing on junk food. Some sleep-eaters even go so far as to cook a meal.
How do people do such complicated things while asleep? Sleep has several stages, which are defined by the different types of electromagnetic wave produced by the brain. An alert brain produces mostly low-amplitude, high-frequency beta waves. As you relax, alpha waves appear, and once asleep, high-amplitude, low-frequency theta waves take over. The next two stages are dominated by large, slow delta waves. These stages are known as non-REM sleep and are deep and dreamless. REM sleep, when dreams occur, is the last stage, just before you start to waken.
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Sleepwalking occurs when a person is roused incompletely and at the wrong point, in the delta-wave stages, and the person becomes stuck in a limbo between sleep and waking: EEG readings of sleepwalkers show a combination of delta waves and higher-frequency 鈥渨akeful鈥� waves. A sleepwalker has no conscious awareness, however, and they won鈥檛 remember anything. There seems to be a rift between mind and body: the cerebellum, which controls automatic movement and coordination, is active, while the frontal and parietal lobes of the brain, which correspond to reasoning and conscious control of movement, are dormant.
What causes people to sleepwalk? Researchers believe that although things like stress and alcohol can provoke it, it mostly comes down to genes. Most sleepwalkers have a family history. It is more common in children than adults, but when it does occur in adults it tends to have more extreme consequences. Sleepwalking has even been used successfully as a defence in multiple murder cases.
Our advice for sleepwalkers? Hide your keys, put the knives away and lock the kitchen door.
