Researchers have found a new mechanism for regulating sleep in the brain

The natural molecule tryptamine can send a signal to the brain about the accumulated need for sleep. Its concentration in the cerebrospinal fluid increased as the animals were awake, and exposure to the receptor associated with it increased the duration and quality of sleep. This was reported on July 22 in the journal Medical Xpress.

Researchers from the Chinese Academy of Sciences and other scientific organizations have studied the mechanism of sleep homeostasis, a process in which the need for rest gradually increases with wakefulness. The experiments were conducted on nocturnal mice and day-active miniature pigs.

Scientists have developed a fluorescent sensor to measure the level of tryptamine in the cerebrospinal fluid. It turned out that the content of the molecule increased during wakefulness and decreased after sleep. This process depended on the duration of the previous activity of the animals, but was not determined by the alternation of daylight and darkness.

Tryptamine was produced by monoaminergic neurons active during wakefulness, located in the medulla and brainstem. Upon release, the molecule bound to the GPR139 receptor and increased the excitability of neurons in the preoptic region of the hypothalamus involved in sleep regulation.

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Tryptamine administration increased the duration of slow-wave sleep and increased slow-wave brain activity. When the researchers suppressed the synthesis of the molecule in individual groups of neurons, the animals lost the restorative sleep that usually occurs after prolonged sleep deprivation.

Additional experiments showed that experimental GPR139 receptor activators increased sleep duration and made it deeper. After local deactivation of the receptor in the preoptic region of the hypothalamus, this effect disappeared. Thus, scientists have identified the tryptamine—GPR139 bundle as one of the mechanisms that transform the accumulated activity of the body into the need for sleep.

On May 24, Medical Xpress magazine reported on the association of sleep disorders with the risk of dementia. According to the publication, sleep is a highly organized state that coordinates chemical processes, vascular movement, and the flow of cerebrospinal fluid. According to scientists, this process is necessary for the operation of the glymphatic system, the brain's purification network.