Research Highlights


Study Explains Role of Brain Chemicals in Sleep

June 1, 2004

Researchers at the Greater VA Healthcare System and UCLA showed for the first time how three brain chemicals-serotonin, norepinephrine and histamine-play distinct roles in regulating sleep. According to the study, serotonin and norepinephrine affect muscle tone, keeping the body still at night, while histamine controls wakefulness. The researchers discovered this by studying dogs with narcolepsy, a sleep disorder. Narcolepsy is marked by a puzzling phenomenon called cataplexy, in which the body goes limp, as if asleep, while the brain stays fully alert. Using sophisticated equipment to monitor the dogs' brain activity, the researchers noted that during cataplexy, neurons with histamine remained active, while those containing serotonin and norepinephrine fell silent.

John J, Wu MF, Boehmer LN, Siegel JM. Cataplexy-active neurons in the hypothalamus: implications for the role of histamine in sleep and waking behavior. Neuron. 2004 May 27;42(4):619-34.