Thanks to DNA mutation, some people only need four hours of sleep

Do you need eight hours of sleep a night or are you gonna be okay on four? 

Is it OK to get 5 hours of sleep?
Is it OK to get 5 hours of sleep?

Biologists examined a family that sleeps much less than average and found that the family members owe their anomalous sleep rhythm to a gene mutation.

Biologist Ying-Hui Fu from the University of California, San Francisco, together with colleagues, analysed the genes of twelve members of a family that only sleeps 4.5 hours a night without getting tired. The researchers discovered that the family members have a mutation in the ADRB1 gene.

When the team then bred rats with the same mutation, the animals slept 55 minutes a day less than their peers. This was accompanied by an abnormal activity in a brain area that regulates sleep: part of bridge of Varolius.

Mutations

Brain cells in this region of the brain, in which the ADRB1 gene is expressed, are inactive in normal mice during most sleep stages. The cells are active when rats are awake. In the mutated rats, the cells are even more active than usual during waking hours. The researchers also discovered that they could wake sleeping rats by artificially activating the brain cells in which ADRB1 is expressed.

All in all, the results suggest that brain cells with ADRB1 promote wakefulness and that variations in the ADRB1 gene affect how long we can stay awake every day, says Fu.

Her team previously discovered that mutations in other genes, such as DEC2, can also cause people to need less sleep.

Imitating ADRB1

The gene mutations found do not seem to lead to negative health effects. Most people who sleep for short periods of time are very happy with their sleep pattern - they usually make the most of the extra time they have," says Fu.

So why don't we all have the ability to function with less sleep? Fu believes that ADRB1 and DEC2 mutations have only recently entered the human genome, and that they have not yet had time to spread widely. 

The 8-hour standard has been the standard for a long time, but somehow new mutations have occurred recently that make this seemingly beneficial property possible,' she says.

Who knows, we may one day be able to develop drugs that reduce the amount of sleep required by mimicking the effects of the ADRB1 mutation. But that's going to take some time, Fu says.