Gene that allows short sleep cycles discovered

WASHINGTON - Scientists have discovered a gene that helps a mother and daughter stay alert on about six hours sleep a night, two hours less than the rest of their family needs...

In 2001, they discovered a mutation that puts its carriers' sleep patterns out of whack: These people regularly go to bed around 7:30 p.m. and wake around 3:30 a.m...

Now the same team has found a gene involved in regulating length of sleep. In one family, the 69-year-old mother and her 44-year-old daughter typically go to bed around 10 p.m., and Mom rises around 4 and her daughter around 4:30, with no apparent ill effects. The rest of the family has typical sleep patterns.

Blood tests showed the women harbored a mutation in a gene named DEC2 that's involved in regulation of circadian rhythms, the body's clock. A check of more than 250 stored DNA samples didn't find another carrier.

Then lead researcher Ying-Hui Fu, a neurology professor, and colleagues bred mice and fruit flies that carried the mutation. Sure enough, the flies' activity and brain-wave measurements on the mice showed those with the mutation slept less — and the mice needed less time to recover from sleep deprivation.

Fascinating. More at the StarTribune link.