Night owls were slightly more likely to die during the study period compared with morning larks, after researchers controlled for other health risk factors, Knutson said.
Night owls also had more health problems — twice the risk of psychological disorders, 30 percent more risk of diabetes, 25 percent increased risk of neurological problems, 23 percent higher risk of gastrointestinal disorders and 22 percent increased risk of respiratory disease.
The study only found an association, and it couldn’t say why night owls have poorer health, but researchers have a couple of theories, Knutson said.
But a more intriguing theory posits that the health of night owls reflects the fact that their internal clock is at odds with the rest of the world.
“The problem may be that a night owl is trying to live in a morning lark world,” Knutson said. “They have to get up earlier for work, perhaps, or if they want to socialize with friends and family that might occur earlier than their biological clock would want.
“There may be this misalignment between their internal clock and their behaviors or environment, and that may lead to problems in the long run,” she added.