Lower metabolism, eating behavior possibly explain the cause of overweight in narcolepsy

Oct 2 2007

A lower metabolism, as well as slight changes in eating behavior, could explain the positive energy balance leading to being overweight in narcolepsy, according to a study published in the October 1 issue of the journal SLEEP.

The study, authored by Dorotheé Chabas, MD, PhD, of the Fédération des Pathologies du Sommeil, Hôpital Pitié-Salpêtriére, Paris, France, focused on 13 patients with narcolepsy and nine healthy controls matched for age, gender and ethnicity. Energy balance was evaluated by measuring the subjects' body mass index (BMI), rest energy expenditure with calorimetry, daily food and water intake and plasma hormone levels. Eating behavior was evaluated using psychometric tests.

According to the results, more narcoleptics than controls tended to be overweight. Seven of 13 narcoleptics and one of nine controls were overweight. Overall, narcoleptics had lower metabolism than controls. Only typical narcoleptic patients (those with narcolepsy with clear cataplexy and with suspected hypocretin deficiency) tended to eat less than controls. Plasma glucose, cortisol, thyroid and sex hormone levels did not differ between groups. However, prolactin levels were twice as high in patients with narcolepsy as in controls. Narcoleptic patients had higher psychometric scores and more frequent features of bulimia nervosa than controls, suggesting a mild eating disorder, classified as “Eating Disorder Not Other Specified.”

“There has been, to our knowledge, no measure of energy expenditure in narcoleptic patients and no ratio between calories intake and energy expenditure in narcolepsy. We, therefore, conducted a pilot study measuring food intake, eating attitude, energy expenditure and basal plasma levels of various hormones in untreated patients with narcolepsy and controls,” said Dr. Chabas.

Narcolepsy is a sleep disorder that causes people to fall asleep uncontrollably during the day. It also includes features of dreaming that occur while awake. Other common symptoms include sleep paralysis, hallucinations and cataplexy.

About one out of every 2,000 people is known to have narcolepsy. The chance that you have narcolepsy is higher when a relative also has it. It affects the same number of men and women.

Those who think they might have narcolepsy, or another sleep disorder, are urged to discuss their problem with their primary care physician, who will issue a referral to a sleep specialist.