Gene identified in people who need little sleep

Health news

Scientists
identified a gene that causes people to naturally sleep less than six and a
half hours each night without any apparent ill effects.

Getting
enough sleep is important for good health and well-being. The amount of sleep
you need changes as you age, and sleep needs vary from person to person. Most
adults need to sleep seven or more hours each night. Not getting enough sleep
can lead to physical and mental health problems.

Healthy sleep involves not only getting enough hours of sleep, but sleeping at the right time of day and having good quality sleep. Good quality sleep means that you’ve gotten enough of two different phases of sleep: rapid eye movement (REM)—the deep sleep in which dreaming happens—and non-REM. You may not be getting quality sleep if you don’t feel rested after you’ve slept enough, you repeatedly wake up during the night, or you experience symptoms of sleep disorders, like snoring or gasping for air.

Previous
studies have led to the identification of over 50 families with people who need
less than six and a half hours of sleep a night to feel well rested. To better
understand why some people need much less sleep than most, a team led by Dr.
Ying-Hui Fu and Dr. Louis Ptáček at the University of California, San Francisco
carried out a study in a family with three generations of naturally short
sleepers to look for genes involved in their unusual sleep patterns. The
research was supported in part by NIH’s National Institute of Neurological
Disorders and Stroke (NINDS). Results were published online on August 28, 2019,
in Neuron.

Using whole
exome genome sequencing, the researchers searched for gene mutations that only
the naturally short sleepers had. They found a rare mutation in the ADRB1 gene
that was being passed through the family. Family members who inherited one copy
of this mutant gene had a shortened sleep cycle. The ADRB1 gene codes for the
β1-adrenergic receptor. Adrenergic receptors are found on many cells in the
body and respond to hormones, including those known to regulate the sleep/wake
cycle.

The
researchers found that certain brain cells expressed high levels of the
β1-adrenergic receptor. These cells were located in a brain region that’s involved
in regulating sleep behaviors called the dorsal pons. The brain cells were
active when mice were in REM sleep or awake, but not during non-REM sleep.

To learn
more about the mutation’s effects in the brain, the researchers created
genetically engineered mice with the altered gene. Mice with the genetic
mutation slept almost an hour less each day than normal mice. They had about
seven minutes less of REM sleep and 53 minutes less of non-REM sleep.

Brain cells
with the ADRB1 mutation showed altered activity and electrophysiological
properties, making them more easily activated. Mice with the mutation showed
increased activity of brain cells with the β1-adrenergic receptor compared with
normal mice.

When
researchers turned on brain cells with the β1-adrenergic receptor during
non-REM sleep using a light-activated protein, the mice woke up. These results
suggest that increased activity of wake-promoting brain cells may be one of the
mechanisms underlying naturally shorter sleep cycles.

“Sleep is
complicated,” Ptáček explains. “We don’t think there’s one gene or one region
of the brain that’s telling our bodies to sleep or wake. This is only one of
many parts.”

Natural
short sleep
ers experience better sleep quality and sleep efficiency,” Fu
says. “By studying them, we hope to learn what makes for a good night’s sleep,
so that all of us can be better sleepers leading happier, healthier lives.”

by Tianna Hicklin, Ph.D.

Source – NIH

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