Research conducted over the years has increasingly linked poor sleep (particularly sleeping less than the minimally recommended 7 hours per night) to the risk of weight gain over time. Not sleeping enough may result in hormonal imbalances that affect appetite, leading some to eat more than they normally would on a healthy sleep regimen.
To investigate in more detail how sleep affects calorie intake, researchers from the University of Chicago and the University of Wisconsin-Madison conducted a randomized clinical trial involving 80 young, overweight adults who habitually sleep less than 6.5 hours a night.
“Over the years, we and others have shown that sleep restriction has an effect on appetite regulation that leads to increased food intake, and thus puts you at risk for weight gain over time,” said lead investigator Esra Tasali, director of the UChicago Sleep Center at the University of Chicago Medicine. “More recently, the question that everyone was asking was, ‘Well, if this is what happens with sleep loss, can we extend sleep and reverse some of these adverse outcomes?’”
The volunteers were randomly split into two groups. One received personalized sleep hygiene counseling, which involved changing one’s routine to avoid the things that hinder sleep (caffeine in the evening, heavy meals close to bedtime, excessively warm bedroom, etc.) and introduce activities that aid sleep (going to bed at the same time, using your sleep only for sleep or sex, etc.). The other group received no intervention at all and acted as a control.
In the first two weeks, the researchers just gathered baseline information about sleep and calorie intake. Sleep patterns were measured using wearable devices while calorie intake was quantified using the “doubly labeled water” method. The doubly labeled water method is a trialed and tested urine-based test for objectively tracking calorie intake, which involves a participant drinking water in which some hydrogen and oxygen atoms have been replaced with stable isotopes that are easy to trace. With this technique, it is possible to measure every calorie a person burned over a one to two week interval, without having to hawkishly record everything a person puts into their mouths.
“This is considered the gold standard for objectively measuring daily energy expenditure in a non-laboratory, real-world setting and it has changed the way human obesity is studied,” said the study’s senior author Dale Schoeller, professor emeritus of nutritional sciences at UW–Madison.
A month after the study started, the researchers found that participants in the sleep intervention group managed to extend their sleep duration by an average of 1.2 hours. Compared to the control group, the sleep intervention reduced the participants’ daily calorie intake by 270 calories, the equivalent of a small meal.
Of important note is that this examination was performed in a real-world setting. Each volunteer slept in their own beds, ate what they wished, wasn’t prompted to exercise, and generally went about their day as they pleased and normally would. That’s in stark contrast to most weight loss studies that are generally short-lived and diligently measure calorie intake by making sure participants only consume a particular offered diet.
The only factor that was manipulated in the study was sleep duration, and this single aspect proved to have a significant impact on the participants’ calorie intake. If the average reduction in calorie intake of 270 calories per day is maintained over the long term, this would translate to roughly 12 kg (26 pounds) of weight loss over a three-year period. That’s on average; some participants consumed as many as 500 fewer calories per day.
“This was not a weight-loss study,” said Tasali. “But even within just two weeks, we have quantified evidence showing a decrease in caloric intake and a negative energy balance — caloric intake is less than calories burned. If healthy sleep habits are maintained over a longer duration, this would lead to clinically important weight loss over time. Many people are working hard to find ways to decrease their caloric intake to lose weight — well, just by sleeping more, you may be able to reduce it substantially.”
In the future, the researchers plan on studying the underlying mechanisms that may explain why more sleep can lead to weight loss. Previous research by Tasali and colleagues suggest that sleep is important for appetite regulation. Limited sleep may drive changes in appetite-regulating hormones and reward centers in the brain that could lead to overeating.
If you struggle with both your sleep and weight, these findings suggest a simple intervention could do wonders: just sleep more. That’s harder than it sounds, but with some hard work, it is possible. According to the researchers, limiting the use of electronic devices before bedtime was a key intervention.
Here are a few tips that may help you clock in more hours of sleep:
- Go to sleep at the same time each night, and get up at the same time each morning, even on the weekends.
- Don’t take naps after 3 p.m, and don’t nap longer than 20 minutes.
- Stay away from caffeine and alcohol late in the day.
- Avoid nicotine completely.
- Get regular exercise, but not within 2-3 hours of bedtime.
- Don’t eat a heavy meal late in the day. A light snack before bedtime is OK.
- Make your bedroom comfortable, dark, quiet, and not too warm or cold.
- Follow a routine to help you relax before sleep (for example, reading or listening to music). Turn off the TV and other screens at least an hour before bedtime.
- Don’t lie in bed awake. If you can’t fall asleep after 20 minutes, do something calming until you feel sleepy, like reading or listening to soft music.
- Talk with a doctor if you continue to have trouble sleeping.
The findings of the new study appeared in the journal JAMA Internal Medicine.