The Science of Sleep
This article appears in the Winter 2009 issue of South Carolina Medicine, a University of South Carolina School of Medicine magazine.
If you're among the one in five adults with sleep apnea, not being able to get a restful night's sleep is a big deal.
It's bad enough that you get drowsy at work, yawn a lot, and feel foggy-headed. Research shows that people who have sleep apnea are also more likely to have a stroke, diabetes, high blood pressure, congestive heart failure, pulmonary hypertension, and memory difficulties.
Sleep apnea-a disease in which the airway narrows during sleep, allowing insufficient oxygen intake-does not afflict only overweight men. While that's a commonly held belief among members of the medical community, only about one-half of all sleep apnea cases occur in overweight people.
"There's a lot more to it than weight," said Antoinette Williams, MD, an assistant professor of clinical internal medicine in the Division of Pulmonology and Critical Care Medicine who studies sleep apnea. "You must also take into account jaw lines and facial structure. Just because you are skinny doesn't mean you can't have sleep apnea.
"As for the disease afflicting mostly men, well, even though 10 to 13 percent of the male population has sleep apnea, about 10 percent of women overall have it, too," she said.
"Sleep is still a young field compared to other parts of medicine: there's not much known, and there's a lot of room for growth," said Williams, a native of Orangeburg, S.C. "Doctors are becoming more aware of it. With the implications of sleep disturbances leading to illness, it is important that they ask about the sleeping habits of their patients."
A 2001 summa cum laude graduate of the School of Medicine, Williams became interested in the study of sleep while completing a two-year fellowship in pulmonary disease at the University of Maryland.
"I did a medical rotation in a sleep clinic," she said. "I first focused on sleep apnea in children. It is not very common in kids, but they do have it. After the apnea gets better or goes away, research has shown that on average the child's grade level goes up one full grade."
Williams' next move was a fellowship in sleep medicine at Maryland, where she studied with Steven Scharf, a professor of medicine and director of the Sleep Disorders Center. She became intrigued by the study of hormonal fluctuations and sleep apnea in women.
"I studied oxidated stress in relation to obstructive sleep apnea," she said. "It was interesting how chemicals and hormones change during sleep, and how different that change is for people who have sleep apnea. It made me begin to question if this is why pregnant women develop diabetes, cardiomyopathy, and other illnesses.
"Research released earlier this year shows there may be a connection between pregnant women who have sleep disturbances or sleep apnea and the number of low-birth or pre-term babies those women have," said Williams, a member of the American Academy of Sleep Medicine. "It was also found that pregnant women who had sleep apnea are at increased risk of developing gestational diabetes."
As they move into menopause, many women experience disruptions in sleep thanks, again, to fluctuating hormones.
"Estrogen protects against sleep apnea, so when the level of estrogen goes down, women may develop sleep apnea or other sleep disturbances," Williams said. "The numbers bear this out: three to five percent of pre-menopausal women have sleep apnea, but that goes up to seven to nine percent after menopause.
"Doctors might not link sleep apnea in women to snoring and daytime sleepiness, as they do with men," she said. "Women are often misdiagnosed when their symptoms are mistaken for those of depression. And it's more likely doctors wouldn't link sleep apnea to post-menopausal women. But it is important that they take it into consideration when a patient comes to them with sleep difficulties."
To add to the body of information about sleep, Williams is conducting research, publishing her findings, and building a sleep clinic.
"Within the next six months to one year, we'll have a dedicated sleep clinic at the School of Medicine," she said. "We'll treat patients with any kind of sleep disorder, from restless legs to sleep apnea. One of my long-term goals is to have a clinic focusing on women and their sleep issues."