Tuesday, December 16, 2008
TUESDAY, Dec. 16 (HealthDay News) -- People who snore burn more calories when they're resting during the day than people who sleep quietly through the night, new research shows.
However, the calorie expenditure doesn't seem to be enough to balance the extra weight that often accompanies the condition, also known as sleep apnea.
"There are a lot of other factors that are going on that lead to a net increase in body weight," said Dr. Michael Thorpy, director of the Sleep Center at Montefiore Medical Center in New York City. "It's not enough to counteract the weight gain from other sources."
The study, published in the December issue of the Archives of Otolaryngology Head & Neck Surgery, may give insight into the basic biological underpinnings of such disorders.
"We want to figure out how to treat people with this disorder. Losing weight dramatically decreases obstructive sleep apnea in those who are overweight. But the success with behavioral interventions and bariatric surgery have been inconsistent," said study author Dr. Eric J. Kezirian, director of the division of sleep surgery at the University of California, San Francisco. "This study examined one of the important ways that obstructive sleep apnea can affect body weight. There are many things we do not understand about the relationship between obstructive sleep apnea and body weight, and this is one."
Obesity and sleep apnea are closely intertwined.
"People with sleep apnea have a greater chance of being obese, and obese patients have a greater chance of having sleep apnea," said Dr. Jordan Josephson, a sinus specialist at Lenox Hill Hospital in New York City and author of Sinus Relief Now.
But it's unclear which is the chicken and which is the egg, Kezirian said.
This cross-sectional study, conducted by Kezirian and senior study investigator Dr. Nelson B. Powell, of Stanford University, measured daytime resting energy expenditure of 212 adults both with and without sleep-disordered breathing. The mean body-mass index was 28.3 (at the high end of overweight).
Researchers measured the severity of the sleeping disorder with the apnea-hypopnea index, which records how many times per hour a person does not breathe for at least 10 seconds (apnea) or has enough of a reduction in air flow to result in a dip in oxygen levels or to wake up from sleep (hypopnea).
Every 10-point increase in the apnea-hypopnea index corresponded with a 27-calorie increase in daily resting energy expenditure. "It's not a lot, but it can add up," Kezirian said.
The results were unexpected, said Dr. David Rapoport, director of the sleep program at New York Universitys Langone Medical Center in New York City. "What they're saying is that these people have a higher metabolic rate which is not accounted for by their being overweight," he said. "People may be sleeping less and burning up more calories or are struggling to breathe and burning up more calories."
Kezirian explained that repeated awakening during the night is like an adrenaline rush, increasing the metabolic rates of even normal patients. "The combination of sleep deprivation and the surges of adrenaline could contribute to the increased metabolic rate during the day," he speculated.
"We have to do more studies to confirm this and to find out exactly what's going on," said Josephson. "[But] this study is important. It shows that people are starting to take this more seriously, and there is good reason to do so. Sleep apnea is the number one cause of heart attack and stroke in patients that have either while sleeping. We also know that snoring is the number one medical cause for divorce."
A second study found that hay fever and other allergic reactions seem not to be linked with snoring or with daytime sleepiness, unless nasal passages are obstructed.
The findings, conducted by researchers at the University of Occupational and Environmental Health in Kitakyushu, Japan, are based on interviews with almost 1,500 daytime workers at an industrial company in Japan.
People with nasal obstruction should inquire about treatment to improve the quality of both their sleeping and daytime lives, the authors stated.