Losing 90 Minutes of Sleep a Night Added a Pound in Six Weeks, Columbia Study Finds

The Study

Adults who lose about 90 minutes of sleep a night for six weeks gain roughly a pound on average, according to a study published in the Annals of Internal Medicine.

Researchers at Columbia University Irving Medical Center ran the study on 95 adults already at risk for heart or metabolic disease. Each participant went through two six-week stretches: one with adequate sleep, one with about 90 minutes less per night. The same people were compared under different sleep conditions.

By the end of the restricted-sleep phase, participants weighed about a pound more on average and had slightly larger waistlines, according to both Fox News and the New York Post's reporting on the findings. They also spent more time sitting. Their moderate and vigorous exercise levels didn't change.

What The Data Doesn't Show

Researchers didn't detect significant changes in body fat or muscle mass during the six weeks. And they didn't track what participants actually ate.

A pound of weight gain without a measured shift in body composition or food intake leaves the mechanism uncertain. Water retention, changes in gut activity, shifts in muscle glycogen storage—none of that can be ruled out from what's been published.

The researchers themselves flagged this limitation. They noted six weeks may simply not be long enough to pick up meaningful changes in body fat, since fat tends to accumulate more slowly than the number on the scale moves.

The Menopause Angle

Dr. Somi Javaid, an Ohio-based OB-GYN and founder of HerMD, was not part of the study but weighed in on why the finding matters beyond a general population. Javaid told Fox News Digital that sleep is central to how the body regulates metabolism, and that women going through menopause face extra risk because sleep problems spike during that life stage.

"We are destroying women's sleep at the exact life stage when their metabolism is least able to absorb the hit, then telling them to eat less and exercise more," Javaid said.

That's Javaid's outside interpretation, not a conclusion the Columbia study itself reached. The study population was adults at risk for heart or metabolic disease generally; it wasn't designed to isolate menopausal women as a subgroup. Javaid's point is a reasonable extrapolation from known biology. Hormonal shifts during menopause do disrupt sleep, and disrupted sleep has been linked to metabolic changes in other research, but her remarks represent clinical judgment layered onto the data, not something this specific trial measured directly.

Javaid also pointed to the American Heart Association's "Life's Essential 8" framework, which added sleep duration as an official marker of heart health alongside diet, exercise, blood pressure and cholesterol. The AHA recommends seven to nine hours a night for adults. "Chronic short sleep is not a lifestyle quirk," Javaid said. "We need to treat sleep as a vital sign of health."

What's Actually Established Versus What's Inference

Proven by this study: cutting 90 minutes of sleep nightly for six weeks correlates with roughly a pound of weight gain and modestly larger waistlines in an at-risk adult population, alongside more sedentary time.

Not established by this study: the mechanism driving that gain, whether it's fat, water, or something else; whether the effect holds beyond six weeks or reverses with restored sleep; and whether it applies the same way across age, sex or health status outside the sample studied.

Both Fox News and the New York Post covered the findings essentially identically, down to quoting the same Javaid remarks, and both flagged the study's limitations around fat mass and diet tracking. Neither outlet overstated the causal claim beyond what the researchers themselves said.

What Comes Next

The obvious follow-up question the study leaves open: does the pound come back off once normal sleep resumes, or does chronic short sleep create a lasting shift in weight regulation? The Columbia team didn't track a recovery phase in the published results, so that answer isn't in yet. Anyone weighing a nightly Netflix binge against an extra 90 minutes of sleep now has a specific number attached to the tradeoff, even if the biology behind it is still being worked out.