They are efficient only after a few hours of sleep

Aug 16, 2009 07:41 GMT  ·  By

We all have at least one friend or family members who seems to be unaffected by the flow of time, and who is able to wake up in the morning after only a few hours of sleep. What to others may seem only like a nap is enough for these people to recharge their batteries and go about their day completely rested up, ScienceNow informs.

“We've believed for a long time that there's a genetic basis [to this behavior],” explains Washington University in St. Louis (WUSL) neurobiologist Paul Shaw. Investigations have revealed that a genetic mutation is actually the trigger for this ability that early risers have. And it's only recently that experts began unraveling the exact mechanisms that allow some to only rest up for a few hours at night.

The basis for this line of research was set up by geneticist Ying-Hui Fu and his team back in 2001, when the expert proved that a mutation in a gene called Per2 was responsible for familial advanced sleep-phase syndrome (FASPS). In this condition, people sleep the normal average of 8 hours, except that they go to bed very early in the evening, around 6 or 7 pm, and wake up the following morning at 3 or 4 am.

“After that was published, a lot of these people [with unusual sleep schedules] came to us. So we started to collect DNA samples,” Fu, who now holds an appointment at the famous Stanford University, in Palo Alto, California, says of the 2001 study. After shifting through the vast data base of genetic material thus collected, Fu and colleagues believe they may have found the gene they were looking for.

According to the team, the mutation that lies in the DEC2 gene is responsible for affecting sleep duration, and not sleep timing, such as the other one. This gene holds the coding information for a protein that is able to turn off the expression of other genes. These latter genes include some that play a crucial part in controlling the circadian rhythm, which tells the body if it's night or day.

In a new study they published in the latest issue of the respected journal Science, the experts revealed that their conclusions were proven by mouse studies. They engineered lab rodents that expressed the mutant form of DEC2, and noticed that these mice slept on average an hour less than those in a control group. In experiments carried out on fruit flies, the team determined that average sleep duration was reduced by 2 hours.

“Genetic control of sleep is going to be complex and is going to include multiple types of genes. It's really an amazing piece of work,” Paul Shaw concludes.