Brain Chemicals Help Keep Our Wakeful Periods Normal

New findings published in the journal Neuron examine certain brain chemicals involved with wakefulness.

When researchers switched off chemicals involved with wakefulness in the brains of mice, they found that animals slept just 65 percent of the normal time.The study authors believe that this discovery may help to control hyperactivity in people with the medical condition mania.

During the study, researchers studied histamine and GABA, which are produced in a primitive part of the brain that is highly similar in mice and humans. As scientists already know that the chemical histamine sends signals to the brain that help make it awake, which is why antihistamines are associated with drowsiness, the new findings suggest that the chemical GABA acts against histamine in ways similar to a chemical ‘brake' preventing wakefulness being too intense.

Findings revealed that both GABA and histamine are formed in the same brain cells, called histamine neurons, which led the scientists to question their function. Altered levels of the GABA produced by the mice's brains measured what changes this had on their brain activity over the day and night.

The study results showed that the GABA chemical developed characteristics similar to a medical condition called mania in which patients experienced restlessness and sleeplessness, which was similar to characteristics of bipolar disorder in humans.

Furthermore, scientists found that compared with the normal mice in the study, those without GABA ran twice as far and fast and maintained or even increased their overall activity over a 30 minute period. They also stayed awake much longer in the day when they would otherwise be asleep, according to researchers. Lastly, they experienced just about 65 percent of the normal amount of non-REM (Rapid Eye Movement) sleep.

"What particularly surprised us was how little the mice were affected by sleep deprivation," said Professor Franks of Department of Life Sciences and the Centre for Neurotechnology at Imperial College London, in a news release. "Normally mice that lose 5 hours of sleep would sleep for longer following this deprivation, and we would see a much lower level of activity. These mice kept up their hyperactive state over the following 16 hours they were awake. They didn't appear to need any recovery sleep at all."

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