True “early birds” may be wired that way. A gene mutation could explain why those people don’t need an alarm clock to wake up way before daybreak.

We’re not talking about beating the buzzer by a few minutes or sparing the snooze button. And it’s not about being up all night, tossing and turning and finally giving up on sleep in the wee hours.

Instead, it’s called familial advanced sleep phase syndrome (FASPS). People with FASPS wake long before the rooster crows, even when work, kids, or other obligations don’t require it.

Rare Condition

FASPS affects about 0.3 percent of all people, estimates researcher Louis Ptacek. Most people aren’t bothered by it, and may like getting things done while everyone else slumbers, he says in a news release.

But other “morning people” don’t like their predawn waking pattern. They aren’t fond of “being out of phase with the rest of the world,” says Ptacek, who works at the Howard Hughes Medical Institute at the University of California San Francisco.

Is Early Rising in the Genes?

FASPS can run in families. Take the family featured in the March issue of Nature. Out of 15 relatives spanning three generations, five had FASPS.

Without time demands, the family members with FASPS went to sleep around 8 p.m., compared to 11:30 p.m. for the rest of the family. The early birds awoke at 4 a.m., while the others woke up at 8 a.m.

Researchers including Ying Xu of the University of California San Francisco probed the early risers’ genes and mental health for clues to their early rising. Then, they went one step further, testing their theory on animals to see if they could create early risers with a little genetic tinkering.

Was Depression to Blame?

Depression can hamper sleep and energy levels. Depression is treatable and common in the U.S., affecting nearly 19 million adults annually, according to the National Institute of Mental Health (NIMH).

Three of the early risers had a history of depression or showed signs of it. A fourth reported a tendency toward wintertime depression.

But depression didn’t seem to be the reason for their unusual hours, say the researchers. The early risers said they had no problem falling or staying asleep and had good energy levels in the morning. Depression tends to disrupt sleep and dull energy levels more than that, say Xu and colleagues.

Plus, the early risers were 20-65 years old (41 years, on average). That’s “well below the age at which the typical early-morning awakening develops in depression,” write the researchers.

Genetic Clue

The early risers had something else in common -- a gene mutation.

When the mutation was inserted in normal lab mice, the mice became “morning mice,” scampering around their cages earlier than usual.

But the same mutation had the opposite effect on fruit flies. That suggests that the gene has some impact on sleep patterns, affecting mammals and insects differently, say the researchers.

They say the finding might one day lead to new sleep disorder treatments. Meanwhile, see a health care provider about sleep problems and/or depression.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Xu, Y. Nature, March 2005; vol 434: pp 640-644. News release, Nature. National Institute of Mental Health.