May 12, 2011

Being a Night Owl Isn't Good For Your Health

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Joseph V. Madia, MD By:

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Sleep disorders lead to poor BMI

(dailyRx News) Staying up until the wee hours of the morning may potentially lead to your weight to increase. Sleep disorder researchers exploring the relationship between the circadian timing of sleeping, eating and body mass index (BMI) report that this up and down relationship was studied for the first time in the United States.

Researchers found that human circadian rhythms are synchronized to the rotation of the earth; i.e., when the sun goes down you are supposed to be sleeping, not eating. When sleeping and eating are not in sync with this internal circadian rhythm, it can lead to appetite and metabolism shifts, which ultimately could lead to weight gain.

"Healthy sleeping habits promote a healthy lifestyle."

Co-lead author Kelly Glazer Baron, a health psychologist and a neurology instructor at Northwestern University Feinberg School of Medicine reports that extra daily calories can mean a significant amount of weight gain if not offset by more physical activity.

Co-lead author Kathryn Reid, research assistant professor in neurology at the Feinberg School added that it isn't known if late sleepers consume more calories because of their natural tendency or because there are less easy , healthy options at night. Think all night fast food joints.

Senior author Phyllis Zee, M.D., professor of neurology and director of the Sleep and Circadian Rhythms Research Program at Feinberg and medical director of the Sleep Disorders Center at Feinberg and Northwestern Memorial Hospital also added the study shows the number of calories consumed are important as well as the time of day those calories are consumed.

Zee anticipates this information may be helpful to people who have difficulty in losing weight and people involved in late night shift work like nurses, factory workers, and doctors.

Northwestern researchers will next engage in a  series of studies to test these findings in a larger cohort study. They hope  to understand the biology linked to the relationship between circadian rhythms, sleep timing and metabolism.

The Study

  • 51 people (23 late sleepers and 28 normal sleepers) average age of 30
  • Late sleepers went to sleep an at average time of 3:45 am, awoke by 10:45 am, ate breakfast at noon, lunch at 2:30 pm, dinner at 8:15 p.m. and a final meal at 10 at night
  • Normal sleepers on average were up by 8 am, ate breakfast by 9 am, lunch at 1 pm, dinner at 7 pm, a last snack at 8:30 pm and were asleep by 12:30 at night 
  • Participants recorded their eating and sleep in logs and wore a wrist actigraph, which monitors sleep and activity cycles, for at least seven days

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Reviewed by: 
Joseph V. Madia, MD
Review Date: 
May 5, 2011

Last Updated:
May 12, 2011