( creatures that have evolved along very ...)Researchers Identify Cause of Early Bird Sleep Disorder

As for the affected individuals, Ptacek said most are able to live normal lives, and some are proud of being able to arise before dawn and get a lot done while everything is quiet. A few, however, are constantly bothered by living out of sync with everyone else's daily schedule.

"Some of them would never come to a doctor" to find out what's going on with their sleep pattern, Ptacek said, "because they aren't troubled by it. Often, they have adjusted and accommodated their jobs to match their ability. But others are bothered by being out of phase with the rest of the world."

He said the FASPS subjects don't seem to sleep any more or less than other people; they just sleep at different times. And there is apparently no connection to the better-known problem called narcolepsy.

Ptacek said it was also found -- in the family's six affected individuals -- that "they all have asthma, and they all have migraine headaches, with aura. Now, that could be purely coincidental, but a more important possibility is that these are part of the same syndrome." So far, however, "we haven't even looked at that yet."

He estimated that a very small number (about .3 percent) of the human population seems to have this "circadian clock" shift. And in earlier research, Ptacek and his colleagues had discovered an entirely different gene that causes a similar clock-shift. Both arise because of so-called point mutations in the genes. This means that altering a single base-pair in the gene's long DNA chain is enough to change a person's sleep behavior. Evidence from tissue culture experiments with the second gene suggests the change causes a protein -- an enzyme called a kinase that is made by the gene - to be less active than normal.

The lead author of the paper in Nature is Ying Xu, a member of the team in San Francisco. Other team members are at the University of Vermont and the University o
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Source:Howard Hughes Medical Institute