Bad news for "night owls": Those who tend to stay up late and sleep in well past sunrise are at increased risk of early death, a new study from the United Kingdom suggests.
The research, which involved nearly half a million people, found that self-described "evening people" were 10 percent more likely to die over a 6.5-year period, compared with self-described morning people.
The findings add to a growing body of research that suggests that being a night owl could have negative effects on health. Many of these effects may be attributable to a misalignment between a person's internal clock, or circadian rhythm, and the socially imposed timing of work and other activities, the researchers said.
"'Night owls' trying to live in a 'morning lark' world may have health consequences for their bodies," study co-author Kristen Knutson, an associate professor of neurology at Northwestern University Feinberg School of Medicine, said in a statement.
The researchers said society needs to recognize that making night owls start work early may not be good for their health.
"This is a public health issue that can no longer be ignored," said study co-author Malcolm von Schantz, a professor of chronobiology at the University of Surrey in the United Kingdom. "We should discuss allowing evening types to start and finish work later, where practical." [5 Surprising Sleep Discoveries]
The researchers also called for more studies on whether night owls can adjust their circadian rhythms so that they become morning people, and whether such an alteration would lower those individuals' risk of health problems.
The study was published Wednesday (April 11) in the journal Chronobiology International.
Studying night owls
The study looked at medical data from about 433,000 people ages 38 to 73 living in the United Kingdom over a 6.5-year study period.
At the beginning of the study period, participants were asked whether they considered themselves to be morning people or evening people, or whether they felt they fell somewhere in between those two groups.
Evening people were at greater risk for certain health conditions, including diabetes, psychological disorders, gastrointestinal disorders, neurological disorders and respiratory conditions, the study found. But even after accounting for these conditions, the study still found that evening people had a slightly higher risk of dying during the study period, compared with morning people.
The study couldn't determine the reason for the link between being a night owl and the risk of early death.
There could be physiological consequences to having a sleep schedule that doesn't match your internal clock, the researchers said. For instance, some studies have found that people with such "circadian misalignment" have impaired glucose metabolism and impaired mood. Getting too little sleep is also known to have negative health effects, but the new study found little difference between the self-reported sleep of morning people and that of evening people, the researchers said.
Certain behaviors could play a role in the link found in this research. For example, some studies have shown that evening people are less likely to eat a healthy diet and more likely to use substances such as alcohol and illegal drugs, compared with morning people.
But regardless of the reason for the link, people may have some control over whether they are morning or evening people, the researchers said.
A person's "chronotype" appears to be about 50 percent genetic and 50 percent determined by the environment, Knutson said.
To become more of a morning person, the researchers recommend that people make sure they're exposed to light early in the morning, but not at nighttime, Knutson said. People should also try to keep a regular bedtime and not let it slip too much later over the weekends.
Original article on Live Science.