Sleep may be as essential as diet and exercise as a key to maintaining a healthy body weight. New research concludes body mass index (BMI) is linked to length and quality of sleep in a surprisingly consistent fashion.

As part of the Integrative Cardiac Health Project at Walter Reed Army Medical Center, researchers analyzed the sleep, activity and energy expenditures of 14 nurses who had volunteered for a heart-health program at the Walter Reed, where the nurses were employed. The program included nutritional counseling, exercise training, stress management and sleep improvement. Each participant wore an actigraphy armband that measured total activity, body temperature, body position and other indices of activity and rest.

“When we analyzed our data by splitting our subjects into ‘short sleepers’ and ‘long sleepers,’ we found that short sleepers tended to have a higher BMI compared to long sleepers. Short sleepers also had lower sleep efficiency, experienced as greater difficulty getting to sleep and staying asleep,” said Dr. Arn Eliasson, the lead investigator.

Overweight participants tended to be more active than people of normal weight, researchers note.  However, even though they took significantly more steps per day, it didn’t reduce in lower weight. “We found so many interesting links in our data. It opens up a number of possibilities for future investigation,” Eliasson said. “Primarily, we want to know what is driving the weight differences, and why sleep and weight appear to be connected.”

He thinks getting less sleep might disrupt natural hormonal balances—for example, reducing the amount of leptin, otherwise known as the satiety hormone. That could cause those short sleepers to eat more. Stress may also play a role in both reducing the length and quality of sleep and increasing eating and other behaviors that may result in weight gain.

“Stress and being less rested may cause these individuals to be less organized than normal weight individuals, meaning they would have to make more trips and take more steps to accomplish the same tasks. This might add to their stress and encourage other unhealthy behaviors like stress eating,”  Eliasson said, noting that more research to evaluate the role of stress in sleep and metabolism is planned.

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