Sleepwalkers sometimes remember what they’ve done

Three myths about sleepwalking – sleepwalkers have no memory of their actions, sleepwalkers’ behaviour is without motivation, and sleepwalking has no daytime impact – are dispelled in a recent study led by Antonio Zadra of the University of Montreal and its affiliated Sacré-Coeur Hospital. Working from numerous studies over the last 15 years at the hospital’s Centre for Advanced Studies in Sleep Medicine at the Hôpital du Sacré-Cœur de Montréal and a thorough analysis of the literature, Zadra and his colleagues have raised the veil on sleepwalking and clarified the diagnostic criteria for researchers and clinicians. Their findings were published in Lancet Neurology.

Question: What are the causes and consequences of sleepwalking?

A.Z.: “Several indicators suggest that a genetic factor is involved. In 80% of sleepwalkers, a family history of sleepwalking exists. The concordance of sleepwalking is five times higher in monozygotic twins compared to non-identical twins. Our studies have also shown that lack of sleep and stress can lead to sleepwalking. Any situation that disrupts sleep can result in sleepwalking episodes in predisposed individuals.”

A.Z.: “Most sleepwalking episodes are harmless. Apart from the fact that the deep slow-wave sleep of sleepwalkers is fragmented, wanderings are usually brief and pose no danger, or when they do, it is minimal. In rare cases, wandering episodes may be longer, and sleepwalkers may injure themselves and put themselves or others in danger: some have even gone as far as driving a car!”

Question: It is said that the sleep disorder mainly affects children. Is this true?

A.Z.: “Many children transitionally sleepwalk between 6 and 12 years of age. It is thought that passing from sleep to wakefulness requires a certain maturation of the brain. In some children, the brain may have difficulty making this transition. Often, the problem disappears after puberty. But sleepwalking may persist into adulthood in almost 25% of cases. It decreases with age, however, because the older you get, the fewer hours of deep slow-wave sleep you enjoy, which is the stage in which sleepwalking episodes occur.”

A.Z.: “Both children and adults are in a state of so-called dissociated arousal during wandering episodes: parts of the brain are asleep while others are awake. There are elements of wakefulness since sleepwalkers can perform actions such as washing, opening and closing doors, or going down stairs. Their eyes are open and they can recognize people. But there are also elements specific to sleep: sleepwalkers’ judgment and their ability for self-thought are altered, and their behavioural reactions are nonsensical.”

Question: According to you, the idea that people are partially awake and partially asleep is something that must be considered in conceptualizing sleepwalking?

A.Z.: “Absolutely. This is one of the points we outline in our article. There are increasing signs that even in normal subjects the brain does not fall asleep in a single block all at once. Sleep may occur in a localized manner. Parts of the brain can fall asleep before others.”

Question: This may explain why the amnesia of sleepwalkers is not always complete. But can sleepwalkers really remember their actions while sleeping vertically?

A.Z.: “Yes. In children and adolescents, amnesia is more frequent, probably due to neurophysiological reasons. In adults, a high proportion of sleepwalkers occasionally remember what they did during their sleepwalking episodes. Some even remember what they were thinking and the emotions they felt.”

Question: Your work has also shown that the behaviour of sleepwalkers is not simply automatic. Can you explain?

A.Z.: “This is another popular myth. There is a misconception that sleepwalkers do things without knowing why. However, there is a significant proportion of sleepwalkers who remember what they have done and can explain the reasons for their actions. They are the first to say, once awake, that their explanations are nonsensical. However, during the episode, there is an underlying rationale. For example, a man once took his dog that had been sleeping at the foot of his bed to the bathtub to douse it with water. He thought his dog was on fire! There was neither the logic nor the judgment typical of wakefulness. But the behaviour was not automatic in the sense that a motivation accompanied and explained the action.”

Question: Another myth you are interested in relates to impact on the waking state. According to you, beyond the nocturnal phenomenon, sleepwalking is associated with diurnal disorders characterized by somnolence.

A.Z.: “Around 45% of sleepwalkers are clinically somnolent during the day. Younger sleepwalkers are able to hide it more easily. Compared to control subjects, however, they perform less well in vigilance tests. And if given the opportunity to take a nap, they fall asleep faster than normal subjects do.”

A.Z.: “Over the last few years, we have shown that the deep slow-wave sleep of sleepwalkers is atypical. Fragmented by numerous micro-arousals of 3 to 10 seconds, their sleep is less restorative. Sleepwalking is therefore not only a problem of transitioning between deep sleep and wakefulness. There is something more fundamental in their sleep every night, whether or not they have sleepwalking episodes.”

Drug May Offer New Approach to Treating Insomnia

A new drug may bring help for people with insomnia, according to a study published in the November 28, 2012, online issue of Neurology®, the medical journal of the American Academy of Neurology.

The drug, suvorexant, blocks the chemical messengers in the brain called orexins, which regulate wakefulness. Other drugs for insomnia affect different brain receptors.

Taking the drug suvorexant increased the amount of time people spent asleep during the night, according to the study. The study involved 254 people ages 18 to 64 who were in good physical and mental health but had insomnia that was not due to another medical condition.

The participants took either the drug or a placebo for four weeks, then switched to the other treatment for another four weeks. The participants spent the night in a sleep laboratory with their sleep monitored on the first night with each treatment and then again in the fourth week of each treatment.

While taking the drug, participants’ “sleep efficiency,” which reflects the total amount of time they slept during a fixed, eight hour time in bed, improved by 5 to 13 percent compared to those taking the placebo. They also experienced 21 to 37 fewer minutes awake during the night after they had fallen asleep than those who took the placebo. “This study provides evidence that suvorexant may offer a successful alternative strategy for treating insomnia,” said study author W. Joseph Herring, MD, PhD, of North Wales, Penn., Executive Director of Clinical Research with Merck, the maker of suvorexant, and a member of the American Academy of Neurology. “Suvorexant was generally well-tolerated, and there were no serious side effects.”

Herring said larger, longer studies have recently been conducted on suvorexant, along with studies to determine whether the drug could be safe and effective for elderly people, who make up a large percentage of those suffering from insomnia.

What Drives Your Daily Biological Clock?

Researchers working with fruit flies say they have discovered one way that the body’s biological clock controls brain-cell activity that influences daily rhythms.

They believe their findings might improve understanding about sleep-wake cycles and lead to new treatments for sleep disorders and jet lag.

“The findings answer a significant question: how biological clocks drive the activity of clock neurons, which, in turn, regulate behavioral rhythms,” study senior author Justin Blau, associate professor in New York University’s department of biology, said in a university news release.

Previous research with fruit flies’ “clock genes” led to the discovery of similar genes in humans, according to the news release.

It was known that biological clocks control neuronal activity, but it wasn’t known how information from biological clocks drives rhythms in the electrical activity of pacemaker neurons that control daily rhythms.

The NYU team looked at pacemaker neurons in the central brain of fruit flies that set the timing of the daily transitions between sleep and wake. They isolated these neurons and identified sets of genes with different levels of activity at dawn and dusk.

Follow-up experiments found that the activity of a gene called Ir was much higher at dusk than at dawn and that it was more active in the pacemaker neurons than in the rest of the brain. The researchers also found that increasing or decreasing levels of Ir affected behavioral rhythms and changed the timing and strength of variations in the core clock.

“We were looking for an output of the biological clock that would link the core clock to neuronal activity,” Blau said. “Ir seems to do this, but it also, remarkably, feeds back to regulate the core clock itself. Feedback loops seem to be deeply engrained into the biological clock and presumably help these clocks work so well.”

The study was published in the October issue of the Journal of Biological Rhythms. Researchers have noted that results from animal studies do not necessarily translate to humans.

NYU researchers find electricity in biological clock

Biologists from New York University have uncovered new ways our biological clock’s neurons use electrical activity to help keep behavioral rhythms in order. The findings, which appear in the journal Current Biology, also point to fresh directions for exploring sleep disorders and related afflictions.

“This process helps explain how our biological clocks keep such amazingly good time,” said Justin Blau, an associate professor of biology at NYU and one of the study’s authors.

Blau added that the findings may offer new pathways for exploring treatments to sleep disorders because the research highlights the parts of our biological clock that “may be particularly responsive to treatment or changes at different times of the day.”

NYU Biologists Uncover Dynamic Between Biological Clock and Neuronal Activity

Biologists at New York University have uncovered one way that biological clocks control neuronal activity—a discovery that sheds new light on sleep-wake cycles and offers potential new directions for research into therapies to address sleep disorders and jetlag.

“The findings answer a significant question—how biological clocks drive the activity of clock neurons, which, in turn, regulate behavioral rhythms,” explained Justin Blau, an associate professor in NYU’s Department of Biology and the study’s senior author.

Their findings appear in the Journal of Biological Rhythms