Restless Legs Syndrome Could Be in Your Genes

Restless legs syndrome (RLS), according to the American Academy of Sleep Medicine, is a sleep related movement disorder that involves an irresistible urge to move the legs at night. It affects five percent to 10 percent of adults; in children the percentage is unknown.

A new study, published in PLoS Genetics, shows that RLS may be genetic. In the study, 922 people with the genes that are linked to RLS were compared to 1,526 healthy people. Seventy-six potential gene candidates were found. The genes were then replicated in 3,935 people with RLS and 5,754 healthy people.

By doing this the results were narrowed down to six genetic regions that are connected with an increased risk of RLS. There were four mutations. Two have already been reported on; however, two of them are new.

TOX3, one of the newly identified regions, is used by the brain to regulate activity. Earlier studies have shown that TOX3 protein protects brain cells from cell death. However, the connection between TOX3 and RLS is not clear.

Juliane Winklemann, a researcher at the Institute of Human Genetics in Munich, Germany, says that the findings of the study will help with creating new treatments for RLS. It will also provide more insight into the cause RLS.

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Researchers Probe Family for Sleepwalking Gene

What’s passed down from your parents, grandparents and ancestors can impact the way you sleep. In some cases, genetics can be beneficial. For instance the short-sleep gene allows people to better cope with sleep loss. Other families have less helpful genes, like vulnerability to insomnia caused by depression. And rarest of all, a few families in the world carry the ticking time bomb of a gene that causes fatal familial insomnia – a degenerative condition that blurs the boundaries between sleep and wakefulness, eventually ending in death.

Somewhere in America, a group of researchers from Washington University School of Medicine have discovered a family with four generations of sleepwalkers. Nine out of 22 members of the family have been sleepwalkers. And they may hold the key to finding the cause - and potentially a cure - for sleepwalking.

So far the researchers have been able to identify the chromosomal location that contains the family’s sleepwalking gene. Further research is needed to identify the exact gene.

It’s been long known that sleepwalking is a highly heritable condition. Sleepwalking and other parasomnias such as sleep talking and bedwetting are not uncommon in childhood. About 10 percent of children sleepwalk compared to only 2 percent of adults.

It appears researchers are closer to learning why that 2 percent still sleepwalk.

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Sleepy Gene Worsens Effects of Sleep Deprivation

Some people are naturally wired to be tired. About 25 percent of people carry a gene variant that makes them sleepier than their peers, researchers have discovered.

The breakthrough explains why you might feel exhausted for staying up a half hour past your normal bedtime while your coworker in the next cubical has no problem regularly burning the candle at both ends.

People with a gene variant called DQB1*0602 are generally more fatigued whether they are rested or not because their sleep is more fragmented, researchers discovered. They spend less time in deep sleep compared to their peers. When they are fully rested, people with the gene variant have less desire to sleep.

The gene variant is closely related to narcolepsy, yet experts say anywhere from 12 to 38 percent of carriers are healthy sleepers who don’t develop the sleep disorder. Some people without the gene variant also develop narcolepsy, although it’s not as common.

The study compared 92 healthy adults without the gene variant to 37 healthy adults with DQB1*0602. Each participant spent a week at a sleep laboratory. For the first two nights they were allowed full rest, with a ten hour scheduled sleep period.
Sleep restriction followed for five nights. Each subject was allowed only four hours in bed and spent the rest of the time reading, playing games or watching movies.

Throughout the study, researchers measured the participants’ sleep quality and tested their memory, attention and ability to stay awake. Each person also reported how sleepy they felt.

When they were allowed full rest, people with the gene variant spent 34 minutes in stage three sleep compared to 43 minutes for people without the trait. After five nights of sleep deprivation people with the variant spent 29 minutes in deep sleep compared to 35 minutes for the control group.

While people with the variant were sleepier and more fatigued, they performed similarly in memory attention and daytime sleep resistance tests.

The findings may lead to changes in the way we look at sleep deprivation. AASM Member and medical director of Minnesota Sleep Disorder Center Dr. Mark Mahowald suggests doing away with sweeping statements about sleep deprivation.

“The implication is that everyone is sleep-deprived and sleep-deprivation does the same thing to everyone, but the tolerance and range of sleep is so different for different people,” Dr. Mahowald told ABC News.

"Our society has equated sleepiness with defects of character, like laziness and depression, but really, some people are generally sleepier during the day. They're more prone to naps, and to sleeping in. We have to accept the fact that sleep duration is genetically determined and not a sign of defect."

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Fatal familial insomnia: a genetic death sentence

There are genetic diseases and then there is fatal familial insomnia. It’s an excruciating death sentence with no cure and no treatments. Doctors can’t even temporarily relieve the suffering caused by months without sleep. For the unlucky few on this earth who inherit fatal familial insomnia conscience reality is no different than dreams and nightmares.

Little is known about fatal familial insomnia. The research is limited to its rare occurrences. Only about 40 families in the world are known to carry the genetic mutation linked to the disorder. For those families, their curse is a dark secret, a time bomb set to detonate sometime mid-life.

Fatal familial insomnia is a prion disease, the same classification as mad cow disease. The genetic mutations cause abnormal proteins to build up in the brain, destroying nerve cells and leaving sponge-like holes.

It’s a progressive disease. At first the symptoms resemble insomnia. Then it causes profuse sweating, accelerated breathing and heart rate and fever. Soon the sleep cycle breaks down, and the boundaries blur between wakefulness, REM sleep, and short-wave sleep. Death occurs after eight to 72 months, either due to a secondary infection or coma.

The disease can be traced back to 18th century Venice to a wealthy and respected doctor, educated by the disciples of Galileo, known as Subject Zero. In his book ‘The Family That Couldn’t Sleep’, Author D.T. Max wrote the doctor found he could stay up all night playing cards or studying medicine. He started sweating more and more, his servants would bring him fresh shirts every day. Months later, he was dead.

His children shared the curse. For each of them, it started with the typical symptoms of insomnia: trouble getting to sleep, and waking up early. That never stopped. Then there were cognitive problems not unlike dementia. By the ninth month of not sleeping, they were dead.

For centuries, this mysterious pattern would repeat itself. Once a prosperous family, Subject Zero’s descendents fell on hard times, poorer and unable to marry because the community learned word of the strange deaths.

Some migrated to other parts of Italy and Europe. Others went to America.

Scientific researchers discovered fatal familial insomnia in the 1980’s, when a descendent of the family named Silvano checked into the sleep clinic at Italy’s Bologna University.

Silvano, once an energetic playboy in his early 50’s, who never had any problem sleeping, suddenly took on the appearance of a sickly old man. His motor skills were staggered and his brain function was unusual. Silvano was neither asleep nor awake.

National Geographic obtained video from the clinic:

Silvano offered his brain to researchers after he slipped into a coma and died. Most of what we know today about fatal familial insomnia is because of Silvano’s offer.

Learn more about fatal familial insomnia on sleepeducation.com.

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Sleep Loss & Weight Gain: Genetic or Behavioral?

There is growing evidence linking chronic sleep loss with an increased risk of obesity. Short sleep durations are associated with higher body mass index (BMI) scores.

What is the nature of this relationship? Is it genetic? Environmental? Behavioral?

A new study provides some intriguing insight. The results were published last month in the Journal of Clinical Sleep Medicine.

The study surveyed 612 pairs of twins. Each pair was raised together in the same household.

They had an average age of about 37 years. They reported their height, weight and habitual sleep duration.

Results show that 25 percent of participants reported sleeping less than seven hours per night. These short sleepers had a higher average BMI (26.0) than those with a typical sleep duration of seven to 8.9 hours per night (24.8).

An adult with a BMI of 18.5 to 24.9 is considered to be at a “normal” weight. An adult who has a BMI of 25 to 29.9 is considered to be “overweight.”

The results were confirmed in an analysis of 423 monozygotic pairs. Each of these twin pairs shares 100 percent of their genetics. Short sleepers again had a higher BMI (25.7) than normal sleepers (24.7).

There also were 245 twin pairs that differed in their sleep durations. An analysis of these pairs also produced similar results. The shorter-sleeping twins had a higher BMI (25.8) than the twins who had a typical sleep duration (24.9).

How strong was the genetic influence on sleep duration? Further analysis produced a modest heritability estimate of 31 percent for sleep duration. In comparison, the heritability estimate for BMI was 76 percent.

There was little evidence of shared genetics between sleep duration and BMI. Common environmental factors also appeared to have little influence on the link between sleep and BMI.

The results support the idea that voluntary sleep restriction affects BMI. This effect appears to be independent of familial factors.

Do you know your BMI? Use the BMI Calculator on the left side of the blog to find out.

Read more about sleep and obesity and sleep and weight gain.

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Bipolar Disorder in Children May Be Linked to a Circadian Clock Gene

A new study found that the circadian clock gene RORB may be involved in bipolar disorder in children.

The study analyzed the genetic make-up of 305 children with bipolar disorder. They were compared with 140 controls.

Results show a positive association between bipolar disorder and four variants of the RORB gene. The authors suggest that this gene may be an important target in the search for the molecular basis of bipolar disorder.

The study also notes that bipolar disorder often involves a decreased need for sleep. This symptom helps discriminate children with bipolar disorder from those with ADHD.

The NIMH reports that bipolar disorder is a brain disorder. It is also known as manic-depressive illness.

It causes unusual shifts in mood, energy, activity levels and the ability to carry out daily tasks. These symptoms tend to be severe.

Bipolar disorder often develops in a person's late teens or early adult years. But some people have their first symptoms during childhood.

The disorder tends to run in families. Children are four to six times more likely to develop bipolar disorder if a parent or sibling has the illness.

Currently there is no cure for bipolar disorder. But ongoing treatment can help control the mood swings and other symptoms.

In 2008 FRONTLINE reported that bipolar disorder was long believed to exist only in adults. But in the mid-1990s it began to be diagnosed at much higher rates in children. Now one million children in the U.S. have been diagnosed with bipolar disorder.

Earlier this year the Sleep Education Blog reported that sleep problems in children may predict the future onset of depression. Learn more about sleep and children.

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