Scientists Probe Sleep Deprivation, Depression Links
Lack of sleep can lift mood, cause euphoria, but hurts body in long run.
Aug. 31, 2010— -- When numerous studies began to suggest that those suffering from the debilitating affects of postpartum depression were helped by sleep deprivation, many women were skeptical.
Postpartum depression affects between 5 and 25 percent of new mothers with symptoms that include sadness, fatigue, anxiety and irritability.
But now, nearly a decade later, new research that is grounded in those controversial sleep studies is providing new insight into the sleep-depression connection.
Sleep deprivation -- for all its ill effects, both physical and psychological -- can trigger a temporary mood shift, and now scientists say understanding how sleep and sleeplessness work might lead them to better treatments for depression.
A 2001 study of women with postpartum depression at the University of San Diego found that after losing just one night's sleep, new mothers' moods significantly improved.
Researchers reported that a sleepless night had antidepressant effects that were "efficacious and rapid." Sleep deprivation, they concluded, was also easy to administer, inexpensive and relatively safe.
"If a depressed mother stays up all night, or even the last half of the night, it is likely that by morning the depression will lift," said Terry Sejnowski, director of the Computational Neurobiology Laboratory at the Salk Institute for Biological Studies.
"Although this sounds too good to be true, it has been well documented in over 1,700 patients in more than 75 published papers during the last 40 years," he said.
"Neuroscience is just beginning to figure out the basic mechanisms of sleep," he said. "In our lifetime, we will have a much better handle on what exactly is going on and how to fix it. But right now, we are in the early stage of discovery and I can't promise a magic pill. But we have the tools to get the answers."
Postpartum depression experts say they have seen the phenomenon.
"A full night of sleep deprivation can snap someone out of depression, but a partial night isn?t very good," said Kathleen Kendall-Tackett, a health psychologist in the pediatric department at Texas Tech University School of Medicine. "And that is basically what new moms are getting."
She said most experts believe that postpartum depression is not physiologically any different from other forms of depression. It just has different stressors.
These sleep studies will "absolutely help women," according to Kendall-Tackett.
More than 20 million Americans suffer from mood disorders, about 9.5 percent of the population of 18 and older, according to the National Institute of Mental Health (NIMH). Major depressive disorders affect 14 million, and are the leading cause of disability for ages 15-to-44.
However, sleep deprivation only brings a temporary lift in mood, and mothers with postpartum depression often return to the blues even after a short nap. But that, suggests Sejnowski, means depression might one day be reversed just as rapidly.
No medical professional seriously believes that forced insomnia might be a long-term cure for depression, but the correlation between sleep and mood may one day yield answers.
"Unfortunately, we have a really primitive understanding of what happens when you go to sleep," Sejnowski said. "But we are beginning to do neurological studies in an area that has been really neglected."
The links between sleep and mood seem to contradict these theories and are still not well understood.
For psychiatrists, having too much or too little sleep can be a sign of mood disorders, such as depression. As a rule, doctors say sleep problems make almost every illness worse.
Sleep and Mood Not Well-Understood
Sleep disturbance is also one of the symptoms on the checklists for diagnosis of both depression and bipolar disorder in the Diagnostic and Statistical Manual of Mental Disorders.
Scientists know sleep is important -- animals do it daily -- but it's still an enigma.
During the first phase, the brain is in deep, slow-wave sleep, with alternating periods of rapid-eye movement (REM) or dream sleep, which is marked by faster brain waves. As the night progresses, REM sleep becomes more frequent.
During the day the neurons in the cortex, or cognitive part of the brain, are active, but during sleep the neurons quiet down.
Using brain imaging, the San Diego researchers found a small area of the cerebral cortex in the front of the brain -- the anterior cingulate cortex -- which was overactive in depressed patients. But after those patients were robbed of sleep, those levels quieted.
Interestingly, antidepressants such as tricyclics and SSRI's block REM sleep. And families with a rare genetic defect that extends REM sleep into earlier in the sleep cycle are more prone to depression, according to Sejnowski.
Scientists see the same effect after sleep deprivation in some healthy individuals. The occasional all-nighter, as all college students know, can sometimes cause a temporary state akin to euphoria.
Emily, a 21-year-old senior at Syracuse University who does not suffer from depression, lost an entire night's sleep last summer.
"I couldn't fall asleep for the life of me," she said. "By the time it got to be three in the morning, I just wasn't tired at all. I just laid in bed until about five."
But instead of feeling shattered and depressed at dawn, Emily, a journalism and political science major, said her mood began to lift and she put on her running shoes.
"It was one of the best runs of my life," she said. "I felt like I had a full night's sleep. I ran two extra miles than I normally do around the campus. I went through neighborhoods multiple times because I just didn't feel tired enough to stop."
"I was more numb or immune to the feeling of pain," said Emily. "This time, it took me longer to reach that point of exhaustion."
In a deep brain stimulation project at Emory University in Atlanta, neuroscientist Dr. Helen Mayberg is testing the theory that there is a kind of mood switch in the brain.
In studies, she implanted a pacemaker-like device in the chest with wires that deliver electrical stimulation to a part of the brain that is close to the anterior cingulate cortex, disrupting neural activity.
Unlike electroconvulsive shock treatment (ECT), the electrical current is gentler and does not cause an epileptic fit.
The patients in Mayberg's study are treatment resistant, even with ECT, and struggled with major depressive episodes for at least one year or more.
"These people are very, very sick," she said. "They are stuck and can't get out of it. They are off the map."
The procedure "allows the brain to go back to normal," said Mayberg, a professor of psychiatry and neurology. "While we get an immediate behavioral change in the operating room, the antidepressant effects require several months to become apparent, and continued stimulation is required to maintain it longterm."
Conventional treatments with antidepressants can take a long time to work and ECT has numerous side effects.
Mayberg and her team have reported a 60 percent response rate among those who are out a minimum of one year. The first patients were operated on in Toronto in 2003.
"People aren't cured, but the continued stimulation seems to be safe and people are staying well," she said.
Earlier studies in sleep deprivation -- the quick fix of losing a night's sleep that soon disappears -- have informed this promising new research, according to Mayberg.
"That was the first clue as to how the switching mechanisms in the brain that hijack mood can be controlled," she said. "There may be a key to these switching mechanisms. Instead of taking a long time to work, we are working toward something that is faster acting."
But, she adds, "It's not a cure - there is a tendency to go back to an abnormal state and we don't understand why."
Don't Discount a Good Night's Sleep
While research is still in its early phases, experts say a good night's sleep continues to be vital to health.
Sleep deprivation comes at a high cost, beyond basic exhaustion: reduced memory and impaired decision-making. It can even trigger a manic episode in people with bipolar disorder and cause epileptic seizures.
The psychological impact also takes a toll on physical health, according to Michele Okun, assistant professor of psychiatry and a research psychologist at the University of Pittsburgh's Sleep Institute.
She is studying how sleep impacts and increases the risk for pregnancy complications and perinatal depression. Research has shown a relationship between disturbed sleep and the inflammatory response associated with cardiovascular disease, diabetes and other metabolic disorders
"When you sleep, you have a reparation of a variety of systems," said Okun. "The immune system is revamped and restored. Growth hormones help repair body tissues."
Though there are many pieces to the sleep puzzle, scientists may one day find sleep-brain biomarkers that indicate who may be more vulnerable to depression and can curtail its onset by paying attention to their sleep habits.
"Feelings and emotions impact one's health through changes in the nervous and immune system just as positive emotions improve things," said Okun. "If you think about sleep, it's a behavior, like eating and drinking water and healthy behaviors like exercising and eating right. And it can be modified."