A randomized trial finds getting more Zs leads to eating fewer calories.

Wouldn’t it be great if you could lose weight by just lying in your bed?

Well it turns out you can, according to a new randomized trial appearing in JAMA Internal Medicine.

The catch? You have to actually be sleeping.

I was fascinated reading this paper, which brings into the real-world data that previously only existed in highly controlled laboratory experiments.  When people sleep less, they eat more.

Prior research in the field has been very consistent. If you take an individual and put them in a sleep lab and force them to sleep only 4 or 5 hours a night, they will eat more calories the next day. The mechanism of this relationship – the hormones, cytokines, and other substances that drive the sleep-hunger axis are still being worked out, but the relationship is clear.

Anecdotally, I totally believe this. It was my post-call tradition when I was a resident to stop at Bocella’s deli in Havertown on the way home.

Their foot-long chicken cheese steak was exactly what I wanted after 30 hours in the hospital.

But it’s one thing to note that people eat more when they are tired. It’s another thing to show that by increasing sleep, we can decrease calorie intake.

To figure it all out, researchers led by Dr. Esra Tasali at the University of Chicago randomized 80 individuals, all of whom were overweight and getting less than 6.5 hours of sleep a night – to receive personalized sleep recommendations – sleep extension - to boost the time spent snoozing, or nothing – just routine study visits.

The recommendations were pretty straightforward – stuff we could all do a bit better I think: decreasing ambient light, creating a bedtime routine, limiting phone and tv use in bed, decreasing caffeine intake and increasing exercise. Importantly, each participant was given a goal bed- and wake-time schedule – an adherence goal.

And the recommendations worked.  After a two-week run-in period, the intervention group got about 1.5 extra hours a night as documented by wrist monitors – and stayed that way for the rest of the 2 weeks in the study.

That’s not the interesting part though. The researchers then dug into the energy balance in these individuals – the calories they were taking in and those they were putting out, using doubly-labeled water to get accurate measurements. They found that the group randomized to sleep longer had a significant decrease in total energy intake – that’s calories in – during the study period, to the tune of around 150 fewer calories per day.  They had no difference in total energy expenditure – calories out.

And, since calories in went down and calories out stayed the same, the intervention group lost weight – about a pound over two weeks.

Now, 150 fewer calories a day may not seem like much – that’s about the amount in half a donut. But small changes in caloric intake add up. There are validated models for this. If this reduction in caloric intake was maintained over time, you might lose a few pounds a year just from sleeping a bit more. That’s a pretty good deal.

And of course, sleep is good for more than just weight loss. Participants in the sleep extension arm also reported having significantly more energy during the day, were more alert, and had a better mood.

Two important take-homes then, from this nice, randomized trial. One – getting more sleep is healthy. Two – getting more sleep is possible. It’s the latter that might have more impact for those of us who struggle to get more than six and a half hours a night. We can do better, if we make a plan. Get some rest.

A version of this commentary first appeared on Medscape.com.