The widening American waistline may be feeding an epidemic of sleep apnoea, potentially robbing millions of people of a good night's rest, a new study suggests.
The research didn't definitively link the rise in obesity to sleep apnoea, and it only looked at 1 520 people, almost all white, in Wisconsin. But study author Paul Peppard believes the findings show a big spike in sleep apnoea cases over the past two decades - as much as 55% - and may translate to the entire United States.
"There are probably 4 million to 5 million people who are more likely to have sleep apnoea due to the obesity epidemic," estimated Peppard, an assistant professor of population health sciences at the University of Wisconsin-Madison. "It's certainly an uncalculated cost of the obesity epidemic, an epidemic of its own."
How the study was done
The researchers looked at adults aged 30 to 70 who were monitored as they slept. About 600 to 700 underwent sleep tests between 1988 and 1994, with some continuing to take part along with hundreds of new participants from 2007 to 2010.
The study considered the participants to have moderate-to-severe breathing problems if they had trouble breathing 15 or more times an hour while sleeping.
Sleep apnea is the main cause of breathing problems during sleep. People with the condition often have trouble staying in deep sleep because their throats close, blocking their airways and requiring them to partially awaken to start breathing properly. They don't realise they're waking up and may become very sleepy during the day.
Besides sleepiness, sleep apnea can contribute to heart and other health problems if untreated and increase the risk of work- and driving-related accidents, according to the US National Heart, Lung, and Blood Institute.
'Addressed and controlled'
The researchers extrapolated their findings to the entire United States and estimated that 10% of men aged 30 to 49 currently have symptoms of sleep apnoea. The study estimates the number is 17% of men aged 50 to 70. For women, the estimate is 3% among those aged 30 to 49 and 9% among women aged 50 to 70.
Among all groups, heavier people were much more likely than thinner people to suffer from the symptoms.
The study estimates that these numbers have gone up by 14% to 55% from 1988-1994 to 2007-2010. Peppard estimated that 80% to 90% of the increase in symptoms is due to the growth in obesity.
But it's hard to know for sure how much of a role that obesity plays in causing more symptoms. While obesity is "almost certainly the biggest factor" in causing sleep apnoea, Peppard said, "there's long list of things that cause sleep apnea or are related to sleep apnea, like being older, being male, having a narrower upper airway, having a genetic predisposition to it..."
What to do? If you don't feel rested after sleeping, Peppard said, talk to your doctor.
The good news is that sleep apnea is treatable. One treatment, known as continuous positive airway pressure (CPAP), is a machine that blows air into the throat to keep it open while people sleep. "It's very effective, but some people don't like to use it," Peppard said.
There's another option that will help in many cases, he said: Weight loss.
Joyce Walsleben, an associate professor of medicine at New York University who studies sleep problems, agreed. "Obesity has to be addressed and controlled," said Walsleben. "That is a message for doctors and patients."
Although the study tied obesity to higher risk of having sleep apnoea, it did not establish a cause-and-effect relationship.
For more about sleep
apnea, try the US National Library of Medicine.