A new study confirms staying up late makes us gain weight. The finding that comes from Sleep and Chronobiology Laboratory scientists at the Perelman School of Medicine at University of Pennsylvania shows sleep and obesity are linked.
Getting less sleep seems to make us eat more; consuming more calories than we need, the study authors say. The more sleep we lose, the more weight we are likely to gain.
For the first-of-a-kind study, researchers enrolled 225 participants for the purpose of observing eating patterns during those ‘late night’ hours. A small group was used as a control.
Those in the study were allowed to eat whatever and whenever they wanted. Meal portions were the same between the two groups.
The researchers found people who stayed up late – in this case after 11 pm - consumed 550 extra calories. The test subjects went to bed at 4 am and awakened at 8 am.
After just 5-nights of sleep deprivation, the participants gained 2.2 pounds. Most of the calories they consumed were from fat.
They also consumed more calories throughout the day, but mostly later in the day; eating less in the morning.
The study also confirmed there are racial differences related to sleep loss and weight gain.
African-American men gained an average of 3.7 pounds after five days, followed by African-American females and white men. Both groups gained nearly 2.2 pounds. White women gained an average of just under a pound.
Kenneth Wright, associate professor in the department of integrative biology and the director of the Sleep and Chronobiology Laboratory at the University of Colorado, Boulder said in a press release, “This provides experimental evidence for what we see in the epidemiological literature: that African-Americans seem to be more influenced by the effects of sleep loss.”
The study is significant for several reasons:
• It is a large study of healthy people
• It took place in a laboratory
• It provides more evidence that inadequate sleep is a contributor to obesity
• It supports the detrimental health effects of shift work
Wright says staying up late occasionally isn't going to be a problem, but consistently losing sleep hours during the work-week could mean significant weight gain over time.
The finding parallels a study result published last week that shows sleep deprivation is a risk factor for type-2 diabetes; mostly from insulin resistance that happens when we sleep less than 7 hours a night.
Canadian researchers highlighted the importance of sleep for weight loss last year in a commentary to a study published in the Canadian Medical Association Journal (CMAJ).
Drs. Jean-Philippe Chaput and Angelo Tremblay wrote "New studies provide evidence that insufficient sleep enhances hedonic (pleasure seeking) stimulus processing in the brain underlying the drive to consume food; thus, insufficient sleep results in increased food intake.”
The researchers aren’t sure why staying up late leads to weight gain, but they do know being sleep deprived makes us want to eat junk food and more calories than we need. If you want to ensure weight gain doesn't sneak up on you, go to bed at the same time, keep your awakening routine consistent, even on vacation, and try to practice mindful eating no matter what time of day or night.