Does insomnia cause depression? Does depression cause insomnia? Chronic insomnia is strongly associated with mood disorders, but which way does the causality run?
I think it's likely that cause-and-effect can go in either direction, but surprisingly, there is little experimental research on the connection between sleep and emotions. What there is mostly tracks the effects of enforced sleep deprivation. A typical experiment restricts the amount of sleep subjects are allowed to get over days or weeks, then measures the resulting cognitive and emotional effects. Such research shows that sleep restriction tends to make people less optimistic and less sociable. One study at the University of Pennsylvania found that subjects limited to four to five hours of sleep per night for one week reported feeling more stressed, angry and sad. Their moods improved dramatically when they resumed normal sleep.
It's difficult to run experiments in the other direction -- that is, to make people stressed, angry and sad for days or weeks and note the effect on their sleeping ability -- but virtually every human being can vouch that emotional upset can severely impact sleep.
While sleep is clearly vital to emotional well-being, what is it, exactly, about sleep that is so necessary? As it turns out, mood disorders are strongly linked to abnormal patterns of dreaming. Rosalind Cartwright, Ph.D., a leading sleep and dream researcher at Chicago's Rush Medical Center and author of The Twenty-four Hour Mind: The Role of Sleep and Dreaming in Our Emotional Lives, has shown that individuals who dream and remember their dreams heal more quickly from depressive moods associated with divorce. Rubin Naiman, Ph.D., a sleep and dream expert on the clinical faculty of the Arizona Center for Integrative Medicine, believes that "dream loss" rather than sleep loss per se, is "the most critical overlooked socio-cultural force" in the development of depression.
This is important information because many medications used to help people sleep also suppress dreaming. These drugs have become some of the most widely used in our society. Many antidepressant drugs suppress dreaming as well.
I think mainstream research tends to discount the value of dreaming because the experience is utterly subjective. Dreaming is a phenomenon of purely individual consciousness, and consequently impossible to thoroughly deconstruct by a community of researchers. But dreaming matters.
If you dislike or even fear dreaming because the emotional content of your dreams tends to be negative, keep in mind that "bad dreams" may serve a vital function. Consider Dr. Naiman's view that dreaming is "a kind of psychological yoga," that contributes to emotional wellness. He says that dreams "in the first part of the night appear to process and diffuse residual negative emotion from the waking day; dreams later in the night then integrate this material into one's sense of self."
The bottom line: There is good reason to believe you must get sufficient sleep, and embrace rather than suppress your dreams, if you want to experience better moods. If you have difficulty sleeping or are not getting enough sleep or sleep of good quality, you need to learn the basics of sleep hygiene, make appropriate changes, and possibly consult a sleep expert. You might also keep a dream journal at your bedside, which will help you develop the habit of recalling your dreams upon waking, which in turn can help you to embrace and value dreaming.
For more on gentle, natural ways to achieve and maintain emotional well-being, visit my website: SpontaneousHappiness.com.
Andrew Weil, M.D., is the founder and director of the Arizona Center for Integrative Medicine and the editorial director of www.DrWeil.com. Become a fan on Facebook, follow Dr. Weil on Twitter, and check out his Daily Health Tips Blog.
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