Dopamine Fends off the Zzzzz's: Chemical Helps Sleep-Deprived People Stay Awake
Saey, Tina Hesman, Science News
A reward chemical in the brain is a real eye-opener.
Dopamine, a feel-good brain chemical, helps keep sleep-deprived people awake, researchers from the National Institute on Drug Abuse show in the Aug. 20 Journal of Neuroscience. Dopamine is also required for the activity of a drug that treats narcolepsy, Japanese and Chinese scientists report in the same issue.
"Dopamine has been a forgotten neurotransmitter for sleep regulation," says Emmanuel Mignot, a sleep researcher at Stanford University. Increasing evidence points to dopamine as an important ingredient in the brain's recipe for promoting wakefulness.
The new findings suggest that dopamine may naturally increase when a person is sleep-deprived, counteracting a revved-up drive to sleep, says David Dinges of the University of Pennsylvania School of Medicine in Philadelphia. Dinges and Mignot were not involved in the studies.
Sleep deprivation affects some people profoundly, impairing their ability to pay attention and lengthening their reaction times, Dinges says. Other people function nearly as well when mildly sleep-deprived as they do when well-rested. The extent to which dopamine rises in the brain after sleep loss may help explain some of the variability in people's abilities to cope with sleep deprivation, Dinges says.
Dopamine has an undeserved reputation, says Mignot. "People think dopamine equals addiction," he adds. But the chemical plays a role in many brain functions.
Nora Volkow of the National Institute on Drug Abuse led a team at the National Institutes of Health in Bethesda, Md., and the Brookhaven National Laboratory in Upton, N.Y. The researchers recruited 15 healthy volunteers and tested each person's memory and ability to pay attention to visual cues after a good night's sleep and after being kept awake all night. A brain scan called positron emission tomography indirectly measured dopamine levels in the volunteers' brains.
Sleep deprivation increased dopamine in the striatum, a part of the brain that registers motivation and reward. Dopamine also went up in the thalamus, a brain region that helps control alertness, when the volunteers were sleep-deprived. Increases in the brain chemical kept the volunteers awake, and those same increases also correlated with the volunteers reporting that they felt tired. …