Researchers in California and Wisconsin tell us, “Sleep duration may be an important regulator of body weight and metabolism.”

So, they studied changes in metabolic hormones and their potential relationship to weight loss.

First, the details.

  • 1,024 volunteers from the Wisconsin Sleep Cohort Study (a study of sleep disorders) were studied.
  • They underwent nocturnal polysomnography (a sleep study) and reported on their sleep habits through questionnaires and sleep diaries.
  • Following polysomnography, morning, fasted blood samples were evaluated for leptin and ghrelin (key opposing hormones in appetite regulation).
    • Leptin is an appetite suppressant; it stops you eating too much as well as makes you more active so you burn off more energy.
    • Ghrelin is a feeding stimulant.
  • Adiponectin, insulin, glucose, and a lipid profile were also measured.
  • Relationships among these measures, body mass index (BMI), and sleep duration (habitual and immediately prior to blood sampling) were examined and controlled for confounding factors.

And, the results.

  • Persons sleeping less than 8 hours had increased BMI that was proportional to decreased sleep.
  • Short sleep was significantly associated with low leptin (less appetite suppression), with a predicted 16% lower leptin for habitual sleep of 5 hours vs 8 hours.
  • They also had significantly high ghrelin (greater appetite stimulation), with a predicted 15% higher ghrelin for nocturnal sleep of 5 hours vs 8 hours, independent of BMI.

The bottom line?

So, participants with short sleep had reduced leptin and elevated ghrelin.

The authors concluded, “These differences in leptin and ghrelin are likely to increase appetite, possibly explaining the increased BMI observed with short sleep duration.”

They continue, “In Western societies, where chronic sleep restriction is common and food is widely available, changes in appetite regulatory hormones with sleep curtailment may contribute to obesity.”

Others have observed an inverse association between sleep and BMI. This study is important because it identifies potential mechanisms underlying the association.

11/27/10 20:39 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.