We know sleep deprivation is no fun—it interferes with concentration, makes you more susceptible to viruses, and encourages overeating, among other inconveniences. But it’s more serious than that, according to sleep researcher Matthew Walker, who says a healthy brain when tired will mimic pathological psychiatric patterns.
As little as one night without sleep is enough to turn a reasonable person into “emotional Jell-O,” says Walker, director of Berkeley’s Sleep and Neuroimaging Laboratory. Researchers have already shown that some sleep disturbance is associated with almost all psychiatric disorders, but Walker’s is the first investigation into what happens to the emotional center of a healthy brain when it goes without sleep.
For his study, 26 adults were divided into two groups; one group were kept awake for about 35 hours, and the other were allowed to sleep normally at home in their own beds. Then both groups were shown a series of images, including disturbing pictures of children with tumors and mutilated bodies, and the participants’ brain activity was measured. Walker and his colleagues discovered that in response to negative images, the amygdala, the part of the brain responsible for the “fight or flight” response, becomes hyperactive without sleep—and logical reasoning goes out the window.
This has implications for professionals whose work requires them to forgo sleep, says Walker. “ER staff, long-haul truckers, pilots, military personnel, and new parents require a considerable amount of controlled emotional responding, founded on the basis of logical reasoning and decision making. It is precisely this neural ability that was disrupted by sleep deprivation.” In upcoming research Walker wants to see if sleep disturbance on a less dramatic scale also negatively affects the brain. “What if people are forced to sleep just five or six hours per night—common in the Western world, and not enough—for, say, one week?” he asks. “Is this sleep curtailment, rather than total sleep deprivation? Enough to trigger similar emotional brain disruptions?”
Another issue raised by his research has potential implications for the treatment of psychiatric patients. Would uninterrupted sleep help the mentally ill function better? “This is the big unanswered question,” says Walker. “We just don’t know if it is the psychiatric illness that is causing sleep problems or the other way around.”
Sleep and Neuroimaging Laboratory researchers have also found that sleep plays an essential role in turning experiences into memories. Next up, Walker will investigate which kind of sleep most aids emotional balance: rapid eye movement (REM) sleep or non-REM sleep. All of his work has convinced him that we do not place nearly enough importance on sleep, “not just at a body level, for metabolism and immune function, but also its critical importance in supporting many brain functions.”