Shedding light on sleep disorders

Monday, December 31, 2007

Along with cold and flu season, holiday stresses and general winter blahs, Seasonal Affective Disorder (SAD), in which sufferers experience symptoms of depression and changes in sleep, hits at this time of year. It’s important to recognize and treat SAD, says Dr. Lawrence Epstein, the past president of the American Academy of Sleep Medicine. He talked to HME News recently about SAD, internal clocks and light therapy.
HME News: What is seasonal affective disorder?
Dr. Lawrence Epstein: It’s a disorder in which people experience a number of symptoms related to changes in light exposure, They tend to experience seasonal onsets of depression, along with a variety of other symptoms including daytime fatigue, insomnia, or increased sleep time, increased appetite—particularly craving carbohydrates. And it becomes something that recurs every year at the same time.
HME: Are some people more prone to SAD?
Epstein: It’s worse in geographic locations in which there is less light. Those rates are higher in the northern U.S. Current estimates say it’s 1% to 2% in states like Florida and 10% up north.
HME: How does light affect sleep patterns?
Epstein: The body has its own internal clock—the circadian rhythm. It controls a lot of things: hormone secretion, blood pressure and sleep cycle. The primary stimulus that affects that internal clock is light. Daytime comes around, the sun comes up, the clock is reset for a new day. When light begins to change it affects that clock and seems to impact mood in some people. There’s a strong relationship between sleep and mood.
HME: How is SAD treated?
Epstein: Light boxes are very effective, even more so than antidepressants. We’ve found that we could change the circadian rhythm with light exposure. The circadian system is sensitive to light at certain times and if you apply light at one time it can shift the internal clock one way, or you can shift the clock in another direction so that it goes in the other direction. People say they can prevent SAD by exposing themselves to light as the days get shorter.
HME News: Does light therapy have any other applications?
Epstein: When talking about circadian rhythm, some problems are not sleep disorders. If you’re a night owl, you can’t function in current society that way, so the options are to be chronically sleep deprived, to find a job that lets you keep the hours you need or you can use light therapy to shift your schedule. It also works for jet lag, shift work disorder and other problems where people can’t make their internal schedule fit with the external schedule they want to be on.
HME: Got any tips for using the light box?
Epstein: Using it in the morning is better than the afternoon or evening. Set up the box, have breakfast, read the paper and you’re good to go for the day.