Insomnia is the lament of many melancholy poets, but researchers, too, have long observed that lack of sleep can cause deep depression.
Last month, scientists out of Norway analyzed survey data from over 10,000 teenagers and found that those with sleep problems were up to four times more likely to self-harm than their more restful peers. These findings, published in the British Journal of Psychiatry, are the latest addition to what we know about the link between mental health and sleep cycles. Amid debates over competing therapies and pharmaceuticals, scientists are starting to pay more attention to what this connection between sleep and mood tells us about our minds and bodies, and how treating the one affects the other.
DEPRESSION AND INSOMNIA COMMONLY OCCUR TOGETHER, AND THEY COMPOUND EACH OTHER
While depression and insomnia aren’t always bedfellows, they often develop in tandem, with each aggravating the other. Constant exhaustion does no favors for one’s state of mind. On the other end, it’s common for those who are depressed to develop sleep problems and lie awake for hours ruminating.
A causal study is difficult to implement, but an article published in the journal Sleep found that people with insomnia were almost 10 times more likely to develop depression than those who fall asleep as soon as their heads hit the pillow.
—“Epidemiology of Insomnia, Depression, and Cnxiety,” by DJ Taylor et. al., Sleep, Nov. 2005
MEN AND WOMEN DON'T REACT THE SAME WAY TO LOSS OF SLEEP
In the area of sleep, as in so many others, women get the short end of the stick.
Researchers Roseanne Armitage and Robert Hoffmann conducted a literature review of research on gender, insomnia, and depression. They mostly looked at results from electroencephalograms, or EEGs, that measured electrical activity in the brain during sleep.
In normal sleep situations, EEG readings don’t reveal any major gender differences. But stressful situations, including a lack of sleep, elicit a more pronounced neuroendocrine response in women, probably because of differences in how their brains are organized. This suggests that biological factors may be partly responsible for women being more vulnerable to developing depression and insomnia.
—“Sleep EEG, Depression and Gender,” by Roseanne Armitage and Robert F. Hoffmann, Sleep Medicine Reviews, June 2001
THE INSOMNIA-DEPRESSION LINK MEANS TREATING ONE CAN HELP THE OTHER
Cognitive-behavioral therapy for insomnia (CBT-I) goes beyond “sleep hygiene,” or the typical advice to avoid coffee before bed and try to wake up at the same time every day. It can involve weekly sessions with a physician working on techniques such as progressive muscle relaxation and using guided imagery to calm a racing mind.
In a Stanford study, depressed participants received an antidepressant medication and either seven sessions of CBT-I or a control therapy, which included only sleep hygiene tips. Both therapies focused only on sleeping better, not on relieving depression symptoms.
Patients in the CBT-I group did sleep better, but, crucially, they also felt less depressed. About 62 percent of the CBT-I group was in remission from depression at the end of the trial, compared to about 33 percent of the control group. The Stanford study was one of the first major ones to reveal the efficacy of these treatments. Although its sample size of 30 was small, several later studies, many funded by the National Institute of Mental Health, confirm the effect.
—“Cognitive Behavioral Therapy for Insomnia Enhances Depression Outcome in Patients With Comorbid Major Depressive Disorder and Insomnia,” by Rachel Manber et al, Sleep, April 2008
INSOMNIA TAKEN TO THE EXTREME—TOTAL SLEEP DEPRIVATION—CAN ACTUALLY HELP TREAT DEPRESSION
In the case of insomnia and depression, too much of a bad thing might actually fix the problem.
Since the 1970s, psychologists have known that keeping people up for one full night can reverse the symptoms of depression immediately, unlike antidepressants that can take weeks to kick in. This counterintuitive effect is successful in about 60 percent of depressed patients, regardless of whether they have insomnia. Researchers think sleep deprivation works because it resets the circadian rhythm, and that the experience of staying up all night for a day or two is fundamentally different from sleeping only five hours a night for months on end.
We don’t know exactly why total sleep deprivation works, but it may have to do with how star-shaped neurons called astrocytes release adenosine, a chemical that controls sleepiness. The more adenosine released, the sleepier people feel.
In 2013, scientists at Tufts used mice to study whether this brain process could be manipulated to mimic the positive effects of sleep deprivation. After confirming that insomnia made the mice act depressed, they gave them a compound that triggered more adenosine and, therefore, more sleepiness. This biochemically imitated the effect of sleep deprivation, even though the mice slept normally. Twelve hours later, the mice didn’t have depressive symptoms; the results lasted for two days.
The Tufts findings suggest that adenosine might be a promising avenue for the development of new antidepressants. They also tell us more about why drastic interventions like deep brain stimulation and electroshock therapy, which also involve astrocytes, work.
—“Antidepressant Effects of Sleep Deprivation Require Astrocyte-Dependent Adenosine Mediated Signaling,” by DJ Hines et al, Translational Psychiatry, January 2013
LIGHT THERAPY IS A PROMISING AVENUE FOR LONG-TERM DEPRESSION TREATMENT, WELL BEYOND SEASONAL AFFECTIVE DISORDER
Despite fast-acting effects, the sleep-deprivation treatment isn’t entirely practical. Not only is staying up all night uncomfortable; the antidepressant effects wear off as soon as the subject nods to sleep.
A recent study, conducted over a longer period of time, found that a limited amount of sleep deprivation combined with light therapy could be a feasible alternative.
Seventy-five patients were randomly assigned to either an exercise group or a “wake group.” In the wake group, patients stayed awake on Monday, Wednesday, and Friday for one week, but did not do so again for the rest of the study. They also used bright light therapy every morning and were generally told not to stay up past midnight.
At the end of 29 weeks, the “wake group” still had far better results than the control group, whose members exercised for 30 minutes daily. The wakers slept better and had a depression remission rate of about 62 percent, compared to 38 percent for the exercise group—suggesting that the combination of sleep deprivation and light therapy could be very effective in the long term.
—“Maintained Superiority of Chronotherapeutics vs. Exercise in a 20-Week Randomized Follow-Up Trial in Major Depression,” by Klaus Martiny et al, Acta Psychiatrica Scandinavica, February 2015
Five Studies is Pacific Standard’s biweekly column that identifies and analyzes the best academic research to deliver new insights on human behavior.