WASHINGTON, D.C. - A little sleep deprivation can cheer up patients with unipolar depression.
The problem is after they go to sleep the next night, they wake up even more depressed.
The link between sleep deprivation and depression isn't exactly new, but a study presented at the recent Biomedicine conference sheds light on why there's an association.
It has to do with how active certain parts of the brain are in metabolizing glucose.
Unipolar depressed patients have much higher glucose metabolism than normal controls, said Dr. Christian Gillin, professor of psychiatry and director of the mental health research centre, University of California, Irvine.
He presented findings from studies looking at cerebral metabolism, sleep and depression.
There is often a connection between sleep problems and depression. "Complaints of insomnia or hypersomnia are exceedingly common in patients with depression," he said.
A large epidemiologic study his centre conducted found about 14% of people who complain of insomnia meet diagnostic criteria for depression.
"If they complain of hypersomnia, slightly less, 13%, will meet diagnostic criteria."
Sleep studies of patients with severe or moderately severe depression show they tend to enter REM sleep unusually early compared to normal controls, some have an extended first REM phase and there's a loss in the deeper phases of sleep. Often, patients complain of early morning awakenings.
Some studies suggest sleep deprivation gives relief to 40% to 50% of patients with unipolar depression.
"A full night or a half night of sleep deprivation shows an antidepressant effect," he said. The effects can be quite dramatic.
"If you have a patient with a severe depression, who can barely talk to you, keep them awake for half the night. The next morning they are lucid; elevated tremendously. They show a complete change in their motor activity, they move much more easily and readily, they can talk much better."
Unfortunately, even a small amount of sleep reintroduces the depression. "In some cases, as little as one minute of EEG recorded sleep puts the patient back into depression. Generally, it takes about two hours. It doesn't seem to be dependent on the stage of sleep."
A study was done to see just what happens in the brain of depressed people before and after sleep deprivation, as well as during regular sleep.
Participants underwent PET scans before and after sleep deprivation to see whether there were any changes in glucose metabolism in their brains.
Two groups of depressed people were used, those who improved after sleep deprivation (responders) and those who did not (nonresponders).
The study included 45 depressed patients -- 15 responders and 30 nonresponders. Fifteen healthy controls were used for comparison.
All patients had mild depression. In order to prepare them for the PET scan, patients needed to be able to stay asleep for at least 32 minutes. While they slept they were infused with fludeoxyglucose for the PET scan.
"It was an awful lot of work preparing these people for this study. We had to have them sleep in the lab for several nights with sham I.V.s for them to get used to it. We couldn't include patients who had short REM sleep, or people who had interrupted sleep or severe depression," he said.
Subjects started their study day at 7 a.m. At about 3 p.m., they got their first scan and were rated for depression.
Then "they'd be kept awake all night long, and we rescanned them in the early afternoon. After that they were allowed to go to sleep." Overall, subjects stayed awake for about 34 hours.
There were noticeable differences in the brains of the depressed subjects who responded to sleep deprivation.
"They didn't say they were feeling great, but they did say they felt better," Dr. Gillin said.
The brains of responders showed some significant differences to those of normals.
Before sleep deprivation, PET scans revealed much higher levels of glucose metabolism in their brains.
"Responders have elevated metabolism in the cingulate area and other areas of the limbic system prior to sleep deprivation. It normalizes after they've missed their night's sleep."
The brains of normals and depressed nonresponders did not undergo significant changes.
While the finding doesn't have any immediate take home clinical applications, it is a valuable research tool, Dr. Gillin said.
"It could be we could use this to predict who's going to respond to antidepressant drugs or other forms of treatment," he said.
"I've struggled to see why this works, it seems so paradoxical. You have a group whose sleep is already screwed up because of the depression, you further screw it up by keeping them awake all night and they get better.
Copyright © 1996 Maclean Hunter Publishing Limited
Reprinted with permission.
Internet Mental Health (www.mentalhealth.com) copyright © 1995-2011 by Phillip W. Long, M.D.