Why lack of sleep keeps some chirpy while others grumpy

WASHINGTON - Ever wondered how some stay perky all day with just a few hours of sleep, while others remain cranky all day? Scientists believe it’s all in the genes.

The study from the University of Pennsylvania School of Medicine in Philadelphia looked at people who have a gene variant called DQB1 *0602 that is closely associated with narcolepsy, a sleep disorder that causes excessive daytime sleepiness.

All of the participants came to a sleep laboratory. For the first two nights, they spent 10 hours in bed and were fully rested. The next five nights they underwent chronic partial sleep deprivation, also known as sleep restriction, where they were allowed four hours in bed per night.

Those with the gene variant woke up on average almost four times during the fifth night of sleep deprivation, compared to those without the gene variant, who woke up on average twice. Those with the gene variant also had a lower sleep drive, or desire to sleep, during the fully rested nights.

Those with the gene variant also spent less time in deep sleep than those without the variant, during both the fully rested and sleep deprivation nights.

The two groups performed the same on the tests of memory and attention. There was also no difference in their ability to resist sleep during the daytime.

“This gene may be a biomarker for predicting how people will respond to sleep deprivation, which has significant health consequences and affects millions of people around the world,” said lead study author Namni Goel.

“It may be particularly important to those who work on the night shift, travel frequently across multiple time zones, or just lose sleep due to their multiple work and family obligations. However, more research and replication of our findings are needed,” she added.

The study appears today in Neurology. (ANI)