A quick “dose” of light rather than a handful of pills may soon prove to be the answer for people who suffer from sleeping problems after a long jet flight or working the swing shift.
Dr. Howard Roffwarg, president-elect of the American Sleep Disorders Assn., predicts that the most effective ways of resetting sleep cycles will likely be based on understanding how changes in body temperature and light affect the brain’s wake-sleep cycle.
“The 24-hour temperature cycle is an important sign of what the sleep-wake cycle is doing,” said Roffwarg, who is a psychiatrist at University of Texas Southwestern Medical Center.
The body’s temperature drops gradually during sleep and rises before waking. “We know that as we change sleep stages, the body temperature changes,” Roffwarg said. “If you try to sleep when your body temperature is on the rise, you don’t sleep long.”
Scientists are working to understand how temperature changes affect disruptions in the body’s circadian, or 24-hour, rhythms. It may explain why people do not do well when they move between time zones or change work shifts frequently.
Some ‘Never Catch Up’
“If you keeping changing time zones or sleep cycle, you never catch up with yourself,” Roffwarg said.
Changes in body temperature also appear to affect bodily functions such as the production of certain key hormones. What researchers do not know is why the body produces most of its supply of adrenal cortisol, the stress hormone, during sleep, he said.
Since exposure to light can affect body temperature, researchers also are studying how environmental light levels affect the brain’s pacemaker and various biological cycles.
In the past, sleep researchers have been able to reset an individual’s sleep-wake cycle naturally over a period of about two weeks. Roffwarg said it now appears that brief exposure to strong light can reset the sleep-wake cycle within 48 hours.
“It may be that we can help people going on trips or facing abrupt shift changes in industry with strategic, short exposures to light,” Roffwarg said.
Jet Lag Booths
Psychologist John Herman, an associate of Roffwarg’s at the medical center here, said he envisions airport booths where long-distance travelers can drop in for a “dose” of light to reset their biological clocks.
Understanding how the sleep-wake cycle works means that doctors can use behavioral means of treating sleep problems rather than rely on drugs, which can have adverse side effects.
It is now understood that insomnia, the inability to sleep, is a symptom, like pain.
“We used to think insomnia was all psychological. Now we know only about 50% to 60% of it is psychological,” Roffwarg said in a recent interview.
About 10% of those who complain of insomnia actually do sleep, but are unable to differentiate between being asleep and awake, Roffwarg said.
The rest have difficulties with breathing or involuntary body movements.
Insomnia as a Habit
Depression, anxiety and worry still are very important components of insomnia that lasts a few nights, but some people develop a persistent conditioned, or learned, insomnia after a temporary loss of sleep.
“A few people begin to get conditioned, and it feeds on itself. They start worrying about it during the day. They approach sleeping hours worrying about not sleeping. They try to sleep, and the more they try, the more difficult it becomes,” Roffwarg said.
For such patients, the bedroom becomes a place where they cannot sleep. Roffwarg said they often think a lot at night, and this type of insomnia seems to be alleviated if the individual can be trained not to think by using biofeedback and relaxation techniques.