About 2 per cent of women and at least 4 per cent of men suffer from obstructive sleep apnea, a condition in which the airway collapses and blocks breathing for 30 seconds or even up to a minute or two.
The brain senses that it isn’t receiving enough oxygen and sends a signal to the person to wake up.
The awakenings are brief enough that people usually are not aware of them, but sleep is disrupted continually throughout the night, leading to daytime fatigue and drowsiness.
Sleep apnea – a Greek word meaning “without breath” – used to be a largely unrecognised condition, but the diagnosis is becoming much more common.
The incidence rises with age: Experts estimate that it affects about 40 per cent of people ages 65 and older.
In women, the prevalence rises steeply after menopause. And as people get older, the throat muscles become more prone to collapse.
Age is not the only factor. Being overweight more than doubles your risk of having sleep apnea, says Dr. Lawrence Epstein, chief medical officer at Sleep HealthCenters, a network of clinics based in Brighton, Massachusetts.
In children, sleep apnea was traditionally associated with enlarged tonsils and adenoids or skeletal abnormalities, which can constrict the airway.
However, doctors are finding that more children are being treated for sleep apnea as a result of being overweight.
Dr. David Gozal, a paediatric sleep specialist at the University of Chicago, says the percentage of obese children being treated for sleep apnea in his programme has increased from 23 per cent in 1995 to more than 57 per cent now.
When a blocked airway prevents oxygen from entering the body, blood vessels constrict and blood pressure rises as much as 25 per cent to 30 per cent, Dr. Epstein says.
The activation of the sympathetic nervous system to make people wake up also increases the heart rate and blood pressure.
Also, sleep apnea causes hormone levels to change in a way that reduces the effectiveness of insulin, leading to higher blood sugar and potentially diabetes, he says.
In obstructive sleep apnea, the muscles in the back of the throat go limp and cause the airway to collapse, leading to laboured breathing and loud snoring.
When a person is overweight, fat tissue in the throat makes the airway narrower and even more prone to collapse.
A person is diagnosed with sleep apnea if he or she has at least five apnea events per hour, accompanied by daytime sleepiness.
But experts say that five events per hour is a fairly mild case.
“They might be waking up hundreds of times during the night,” said Sonia Ancoli-Israel, Professor of Psychiatry at the University of California, San Diego.
For those with more stubborn cases, the most common treatment is continuous positive airway pressure, or CPAP
. There are many versions, though they all include a mask hooked up to a machine that blows air into the airway, acting like a virtual splint to help keep it open.
Some masks cover the nose and mouth, while others cover the nose only or use tubes to blow air directly into the nostrils.
When used properly, CPAP is extremely effective. But not everyone wants to wear a mask to bed. “It’s not very pretty, it’s not very sexy and it can be uncomfortable at first,” Dr. Ancoli-Israel says.
One new alternative is Provent, a much smaller device that emulates CPAP but uses the pressure created by a person’s own breathing to maintain airflow.
Dental mouthpieces are another option for treating mild to moderate sleep apnea, especially for patients who are only modestly overweight.
The drawback with all of these approaches is that they must be used indefinitely – none offers a cure.
Though there is no perfect solution for sleep apnea, experts stress the importance of sound sleep. “This is a very serious disorder,” Dr. Ancoli-Israel says. “There are consequences to not getting oxygen to your brain at night.”