Staying up late could be bad for your health - and your waistline
A new study suggests that the health effects of sleep aren't just about how much of it we get but also about when we get it. And a more evening-driven schedule, the researchers found, could be less healthy than a morning one.
The study found that people who identified themselves as "evening types" were significantly more likely to have conditions linked with high blood sugar (which can be linked with a variety of other health problems) than those who identified as "morning types."
It's important to keep in mind, however, that while the study found links between later sleep schedules and certain health outcomes, it did not find that later schedules caused these health comes.
The male night owls in the study were more likely to have diabetes, while the women who stayed up late were more likely to have high blood sugar levels, excess body fat around the waist, and abnormal readings on a group of blood tests used to estimate someone's risk of developing heart disease.
If blood sugar levels stay high enough for long enough periods (a condition known as hyperglycemia), this can contribute to a variety of other health problems, from heart disease to eye, kidney, and nerve damage.
The study had its limitations, of course.
For starters, all of the 1,620 people they studied (who were gathered from a larger Korean genetics study), were in a pretty small age bracket - between 47 and 59. This is right around the time when most of us (yes, even some of the staunchest night owls) start falling asleep and waking up earlier. By the time we reach about age 60, most of us identify as morning people.
It makes sense then that just 6% of them, or 95 people, said they were "evening types," while 480, or nearly a third of them, identified as "morning types." (The rest of the participants said they didn't think of themselves as either a morning person or a night owl.)
Still, the new research builds on some previous findings about how our morning and evening routines affect our health.
A 2013 study in mice, for example, found that one of the key cells involved in helping us fight off viruses and disease is controlled by our cycles of light and dark. When the researchers messed with the mice's natural cycles - shifting their light/dark exposure by several hours every few days for several weeks - the mice were more likely to develop inflammatory disease than the ones who continued with their normal light/dark cycles.
Artificial light at a non-natural time seems to have adverse effects on health.
While genetics is partially to blame for whether we're morning or night people, recent research suggests that another part of the puzzle is our behavior. In other words, if you want to become a morning person, you might actually be able to.
So give it a try - after all, why not?