Researchers say that people with night eating syndrome appear to have disturbed circadian rhythms of food intake. Circadian rhythms are the cycle that your body operates on -- your body's 24-hour clock.
Night eating syndrome is seen in about 6% of people who seek treatment for obesity, according to Albert Stunkard, MD, emeritus director of the Weight and Eating Disorders Program at the University of Pennsylvania School of Medicine. Night eating syndrome may also run in families.
First described by Stunkard in 1955, night eating syndrome may be stress related and is often accompanied by depression. Individuals with the disorder eat one-third or more of their daily calories after their eveningmeal, sometimes rising from their beds once or twice a night to snack.
Speaking at the North American Association for the Study of Obesity (NAASO) annual meeting this week, Stunkard presented some of his latest findings.
In his new study, Stunkard and colleagues monitored sleep/wake activity over one week in 55 obese adults withnight eating syndrome. Participants were compared with 60 people of similar weight who did not have night eating syndrome.
The researchers found that night eating syndrome involves a disturbed circadian rhythm of food intake while circadian sleep rhythm remains normal.
"The circadian rhythm of food intake is extremely disturbed and the timing is delayed by 4 or 5 hours compared to that in normal people," Stunkard tells WebMD.
According to the researchers, night eating syndrome "is the first clinical disorder to manifest different circadian rhythms of two biological systems."
Stunkard also found that 36% of those with night eating syndrome had at least one first-degree relative with the disorder, compared with 22% of those who were not night eaters.
In a separate study of 17 night eaters, 29% of patients taking Zoloft experienced total remission of the disorder, and 18% improved significantly. This study was funded by the National Institutes of Health and Pfizer Pharmaceuticals, the manufacturers of Zoloft.
On average, nighttime awakenings fell by 60%, nighttime eating by 70%, and number of calories eaten after supper by 40%, they report.
A paper describing these research findings will be published in the January issue of the International Journal of Eating Disorders.
With reporting by Emma Hitt, PhD.