There are many reasons why working odd hours sucks. Not only does it severely impinge on your social life and your ability to be out in the sunlight, studies have also found that having a disrupted sleep schedule increases your risk of obesity and diabetes. But they've never been able to understand why until now. A new study has found that sleep disturbances actually have major effects on your metabolism and on insulin levels, which could have serious ramifications for shift workers of all kinds—bartenders, doctors, cops, you name it—and for people who suffer repeated sleep disturbances, such as pilots who often have jet lag from traveling.
The study was led by Dr. Orfeu Buxton, an assistant professor in the division of sleep medicine at Harvard Medical School. He and his fellow researchers had 21 people come and spend five weeks in a highly controlled laboratory setting. This extended period gave them a chance to observe how the people slept, ate, and exercised, and it made it possible to manipulate their schedules and analyze the effects of chronic changes to their circadian clocks. Jeeze, nothing like a little forced sleep deprivation to make for a nice long stay in the lab.
They started out letting people sleep on a normal night schedule where they were getting ten hours of sleep. (Sounds divine!) Then they gradually reduced the amount of time each person slept. The participants were also asked to go to bed and wake up four hours later for a period, which simulated the effect of traveling to different time zones each day. After a number of these incremental changes, the people slept during the day and were awake at night, like people who work the night shift would be. It sounds pretty torturous to put your body through so many adjustments, and, in fact, the effects on the volunteers' bodies were pronounced.
By the end of the five week period, the resting metabolic rate of the participants was eight percent lower than were they'd begun. Buxton calculated that would amount to a ten pound weight gain if your metabolic rate was slowed like that for an entire year—and that's if your diet and exercise routine remained the same. This lower metabolic rate could certainly help explain why night shift workers have a higher risk of obesity than those who are on the day shift. And, of course, any added weight puts you more at risk for diabetes and other metabolic problems.
What was particular fascinating, though, was the discovery that when people were awake at night and asleep during the day, they didn't get as good a sleep, and this affected their insulin levels. After they'd been in the lab for three weeks, the volunteers' insulin levels were down, according to Time:
The participants produced about a third less insulin from the pancreas in response to meals; with less insulin available to break down glucose, blood glucose levels started to rise and three of the 21 volunteers showed high enough levels to qualify them as pre-diabetic.
Yikes. That is fast to go from being fine to heading toward diabetes. It's enough to make insomniacs everywhere tremble in fear. However, the good news is that as soon as they went back to sleeping on a typical night schedule their blood glucose levels went back down.
What all of this put together indicates is that disrupting a person's circadian rhythm is different than simply depriving them of sleep. Trying to force your body onto a different clock can have a real impact on your health over the long-term. Just the altered sleep schedule alone is enough to put you at risk, but Buxton also points out that when you're chronically tired, all sorts of other things go downhill, like your willingness to exercise and your ability to make good food choices. Ugh. No pressure. You're only killing yourself slowly by going to work every night. Of course, don't get too down on yourself. The rest of us are probably doing the very same thing by sitting at our desks all day. God, even just thinking about all of this is exhausting. Let's all take a nice long nap.