Not getting enough sleep can make you groggy, but can it also make you fat? Researchers at the University of Chicago think it’s a strong possibility.

In a new study published in the Annals of Internal Medicine, researchers determined that four nights of sleep deprivation reduced insulin sensitivity in fat cells by a whopping 30 percent. And the less sensitive your cells are to insulin, the less your body produces the hunger-regulating hormone leptin.

“This is one of the first studies to show that a cell outside of the brain—the fat cell—also needs sleep,” says study author Matthew Brady, Ph.D., vice-chair of the Committee on Molecular Metabolism and Nutrition at the University of Chicago.

Brady and a team of researchers put seven young, healthy subjects through two study conditions: First, they spent 8.5 hours in bed for four nights in a row (participants slept for roughly 8 hours each night, the ideal length). One month later, they spent 4.5 hours in bed for four nights. Previous research has shown that getting only 4 hours of sleep negatively affects metabolism. After the fourth night, the subjects took a glucose tolerance test and had fat cells biopsied. And, yes, food intake was controlled and identical.

How Sleep Affects Fat
The authors found that sleep deprivation made fat cells less sensitive to insulin, a hormone that cells use to take in glucose for energy. Brady explains that insulin-stimulated glucose uptake is proportional to the secretion of leptin, a hormone made in the fat cell that regulates hunger.  The less sensitive cells are to insulin, the less leptin they produce, and the hungrier you are. And the magnitude of the decrease in this case was very surprising.

“A 30 percent reduction in insulin sensitivity is equivalent to metabolically aging the subjects 10-20 years just from four nights of four and a half hours of sleep,” Brady says.

“It’s not that we took someone who was on the tipping point of developing metabolic disease and just pushed them over the edge. These were very young, healthy subjects.”

Brady says the findings are important because they suggest that sleep could be a treatment for obesity. To that end, his next study will consist of trying to improve the sleep of overweight or obese subjects who have obstructive sleep apnea to see if sleep quality has any effect on insulin sensitivity and metabolism. He’s excited about the possible impact such a study might have: “It’s hard to get people to diet and exercise but if you could show that improving your sleep quality and duration has a positive benefit, that may be an easier therapeutic intervention for people to undertake.”

Ways to Get Better Sleep
While this study still leaves some questions unanswered—namely, if sleeping, say, 6 hours is bad or if “catching up” on sleep over the weekend can reverse the effects—it’s clear that getting enough sleep is important for both your mind AND your body. Here are five ways you can improve your sleep now.

1. Make a Bedtime Routine
Pick an hour for shutting down every night and stick to it—on weekends, too. A regular bedtime and waking time will help you fall asleep.

2. Power Down
Checking your cell before bed amps up brain activity, making it harder to doze off. Plus, the blue light emitted from gadgets can suppress the sleep hormone melatonin. At least an hour before bedtime, turn off your TV and computer and don’t use your phone.

3. Chill Out
A cooler body makes it easier to fall asleep. Exaggerate that feeling with a toasty, pre-bed bath or shower. Lower your thermostat a bit, then pile on the blankets—you’ll save money on your heat while you’re at it.

4. Sip Wisely
No caffeine after sundown and no booze before bed. While drinking alcohol may help you fall asleep faster, you could wake up in the middle of the night. Enjoy a cup of decaf or herbal tea instead.

5. Drown Out Noise
Sleep with a fan on or invest in a sound machine that can produce white noise to block the racket of the outside world.

Additional reporting by Katie Connor and Loren Chidoni

More from WH:
Yoga Poses That Put You to Sleep
10 Sleep Myths Busted
Your Brain On Sleep

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