Chances are, too, there are far more extreme larks than come to professional attention. The team pointed out that people with advanced sleep phase rarely consult sleep doctors or are studied in sleep clinics because most of those affected seem to like the pattern, perhaps because it fits well into the rhythm of their lives or they have selected or created a rhythm that fits into their sleep-wake needs.

The incidence of advanced sleep phase disorder is likely underestimated because it results in fewer social conflicts. People are not usually penalized for getting to school or work too early. Night owls, on the other hand, are more inclined to seek the help of a sleep specialist because it’s so hard for them to get up and get going in the morning to meet the demands of school, work or household.

“People with delayed sleep phase often suffer a great deal,” Dr. Ptacek said. “They may be unable to fall asleep before 2, 3 or 4 a.m. and then have to get up at 7. They tend to be chronically sleep-deprived and may not function well.”

Still, like my friend, not every early riser is happy about it. Dr. Ptacek told of one woman who at age 40 was getting up involuntarily at 4 a.m. and at age 50 at 3 a.m. Finally, at 69, she sought help from a sleep specialist because she didn’t like getting up at 2 in the morning when it was “cold, dark and lonely,” then being too sleepy to attend social events in the evening. “She was depressed because no one took her seriously and people thought she was being unfriendly when she declined their evening invitations,” the neurologist said, adding that the woman is now 90 and wakes up at 1 a.m.

[Are you a night owl or a morning lark? Take a quiz.]

I asked Dr. Ptacek whether advanced or delayed phase sleepers have to capitulate to their genetic heritage or might they be able to induce a more normal day-night schedule. He told me that in effect, it requires adopting behaviors like those used to overcome jet lag.

For example, exposure to bright light in the evening — especially the blue light from cellphones and most e-book readers — can delay the biological clock and help people to stay up later (or, in the case of insomniacs, make it harder for them to fall asleep). Those with a delayed sleep phase need exposure to bright morning light to stimulate arousal.

Taking melatonin might help, but only if it’s timed correctly. Naturally, melatonin levels begin to rise about two hours before sleep, so it may help night owls fall asleep earlier if it is taken orally two hours before their desired bedtime.

For those who awaken in the middle of the night, Dr. Ptacek advised getting regular exercise, avoiding a big meal close to bedtime and not stressing about not sleeping. “The more anxious you are, the less likely you’ll be able to fall back to sleep,” he said. Instead, he suggested, “Get up and do something kind of boring for an hour or so and then go back to bed.”