Study Reveals Why All-Nighters May Be So Dangerous for Your HealthSouffleur
Shifting your sleep schedule may trigger changes in the body that can eventually lead to obesity, diabetes, and other serious problems.
You know sleep is important. We’ve all heard about the harmful effects of regularly not getting enough restful sleep, such as increased risk of heart disease, diabetes, high blood pressure, stroke, obesity, and more. But new research offers new evidence on why when we sleep may be of utmost importance when it comes to how those poor-sleep-related problems actually develop.
A study published May 21, 2018, in the Proceedings of the National Academy of Sciences (PNAS) showed that staying awake at night and sleeping during the day for even just one 24-hour period can rapidly lead to changes in more than 100 proteins in the blood, including ones that have an effect on blood sugar, immune function, and metabolism. Over time, these biochemical changes in blood protein levels can elevate your risk for health issues such as diabetes, weight gain, and even cancer, says the study’s lead author, Christopher Depner, PhD, a postdoctoral fellow in the department of integrative physiology at the University of Colorado in Boulder.
Altering Sleep and Eating Patterns Leads to Dramatic Changes in Your Blood
Previous research has shown that night-shift work is a risk factor for weight gain and other metabolic disorders. “We know that shift work is associated with increased weight gain, obesity, and diabetes,” says Dr. Depner. To investigate the possible ways that circadian misalignment (eating at night and sleeping during the day) can lead to health problems, Depner and his colleagues set out to examine the ways reversing the sleep-wake cycle affects protein levels in human blood.
The study participants were six healthy men in their 20s with regular sleep schedules (sleeping an average of eight hours at night), who spent six days in a research center at the University of Colorado Hospital. During their stay, researchers strictly regulated their meals, sleep, activity, and exposure to light.
After spending the first two days following a traditional sleeping and eating schedule (where they slept at night and consumed their meals during the day), the men were gradually transitioned to a simulated night-shift sleeping and eating schedule. On these altered-schedule days, the men were kept up all night and allowed to sleep for 8 hours during the day. On these days, they also ate their meals at night.
The researchers took blood samples from the men every four hours. They found that of the 1,129 proteins being studied, as many as 10 percent, or 129 proteins, were altered by the simulated night shift. Proteins that would normally be more prevalent in higher levels during the day were peaking at night, and vice versa. The researchers were surprised by both the magnitude and amount of these biochemical changes, Depner says. “They changed so much and so rapidly — and these changes happened by the second day.”
Proteins That Regulate Blood Sugar Levels and Calorie Burning Were Thrown Out of Whack When Sleeping and Eating Were Shifted
One of the proteins was glucagon, a key hormone that causes the liver to secrete blood glucose and helps regulate blood sugar levels. During the simulated night-shift phase of the study, glucagon levels rose at night rather than the day and peaked at levels that were higher than in the daytime. “We know that over time, this would be a primary risk for diabetes,” Depner explains.
Another protein that was affected by the night shift was FGF19, or fibroblast growth factor 19, which animal studies have shown can boost calorie burning. On the days when sleep and eating were shifted, the FGF19 levels decreased, which researchers say may be one explanation for why the study participants burned 10 percent fewer calories per minute during these night-waking periods.
“[FGF19] changed in a way that would decrease the energy the body uses,” Depner says — which could lead to weight gain if the pattern continued over time.
The study also identified 30 proteins that fluctuated depending on the time of day, regardless of when an individual slept or ate.
Because light is known to play a significant role in keeping our circadian systems on track, the researchers made sure the participants were in dim candlelight without any exposure to electronics or artificial light at night, notes Depner. Despite this, researchers saw clear changes in protein patterns. “We eliminated cell phones and screens, but still saw negative consequences,” says Depner, meaning that while light may be a factor, it’s not the only one that affects the body’s circadian system and the other processes it influences.
This Study Was a Small One, but the Results Are Important, Experts Say
Though small, this study is one of the first and most revealing to look at how protein levels in the blood are affected by when we eat and sleep — and shows what’s happening to those protein levels in real time when those everyday patterns are altered, Depner says. The results emphasize the important role our body’s circadian clock plays when it comes to our health.
The study illuminates potential ways that circadian misalignment (that is, sleeping and eating when our body clocks aren’t expecting it) can lead to disease by identifying proteins affected by those factors, says Eve Van Cauter, PhD, a professor of endocrinology, diabetes, and metabolism in the department of medicine at the University of Chicago, who was not involved in the new study. “We know shift workers are at increased risk of diabetes and cancer, but we don’t know the pathway,” says Dr. Van Cauter. “This study is pointing at the pathways.”
While this study is definitely an important step in understanding the ways in which circadian misalignment can lead to health problems, it’s worth noting that it involved only six men, who were young and healthy, notes Depner. The researchers plan to do future studies on larger groups of people including women.
Another limitation was the frequency of the blood tests, notes Van Cauter. In this study, blood samples were taken only every four hours. “While informative, the sampling was infrequent — given that the entire 24-hour cycle only had six data points,” says Van Cauter.
Our biological patterns can’t always be adequately captured in four-hour increments, she adds. “Human rhythms are more complex.” (Though, she adds, increasing the frequency of the blood tests would have increased the cost of the research significantly.)
Bottom line: If you’re someone who regularly pulls all-nighters or has to work regular night shifts, it’s important to keep in mind that there are clear health consequences and costs of being a night owl. These findings show that “even in healthy people, you can see the negative effects of [a shifted sleep, waking, and eating schedule],” says Depner. Talk to your doctor about ways to stay healthy if your job or other factors do require you to shift your sleep schedule. And if your job and lifestyle do allow you to follow a regular sleep schedule (sleeping at night and eating during the day), this study offers more evidence that doing so could have big benefits for your health.