In addition to night owls and morning larks, the New York Times notes there are people whose sleep-wake cycle is out of sync with the modern world and that that too might have genetic roots.
Researchers led by University of California, San Francisco's Louis Ptacek collected data on more than 2,000 people and their preferred chronotype — when they liked to go to sleep and wake up — who came to a sleep center. As they report in Sleep, they found that familial advanced sleep phase was more common than they'd expected, affecting 1 out of every 475 patients presenting at a sleep clinic.
Advanced sleep phase, the Times notes has been linked to a single dominant mutation. "But while this mutated gene travels in families, its expression can vary based on what the rest of the genome looks like," Ptacek tells the Times.
Ptacek suggests that people who find themselves staring at the clock in the wee hours avoid eating close to bedtime and get regular exercise. He also tells the Times being anxious about not falling back asleep will only make it worse and advises getting up to "do something kind of boring for an hour or so and then go back to bed."