Scientists have discovered a genetic disorder which they say is responsible for people who find it impossible to stay up late or sleep in. The findings could lead to new treatments for jet lag, insomnia and seasonal depression.
The researchers from the University of Utah say people who cannot stay awake much after 8.30pm and who wake up around 5.30am may be suffering from a disorder called "familial advanced sleep-phase syndrome". This means the person's body clock is three to four hours faster than normal.
Writing in Nature Medicine, the scientists, led by Dr Louis Ptacek, say they found 34 people in three families who suffered from the disorder. In one family, a grandmother, daughter and grandchild all had the disorder which is not the same as simply finding it difficult to stay in bed in the morning.
Scientists hope that by studying the syndrome they may be able to identify the gene responsible.This could lead them to the protein it produces to cause the shortened time clock which, in turn, could be used to formulate new drugs to treat jet lag and other conditions. However, they admit that it will take some time to isolate the gene.
David Earnest of Texas A&M University said: "This is the first time that anyone has identified a genetically inherited trait that involves the expression and control of the circadian rhythm in humans. That's really critical." He added that finding the key to different patterns of circadian rhythm could help researchers to discover their role in jet lag, seasonal affective disorder and other mental health problems.