Newly identified molecule could help regulate sleep - Medical Xpress

What the report says

Medical Xpress reported on July 22, 2026, that researchers in China have identified a naturally occurring molecule, tryptamine, that may help signal the brain’s need for sleep. The work, led by Huateng Cao, Kui Wang and colleagues at the Chinese Academy of Sciences and other Chinese institutes, was published in Nature Neuroscience and examined sleep-related mechanisms in mice and pigs.

According to the report, the team studied cerebrospinal fluid and found that tryptamine levels rose as animals stayed awake and active, matching what scientists call sleep pressure. This pattern appeared in nocturnal mice and diurnal pigs and was reported to be independent of light-dark cycles. The researchers also found that wake-active neurons in parts of the brain produced and released the molecule.

The study suggests tryptamine acts through a receptor known as GPR139, increasing activity in the hypothalamic preoptic area, a region associated with promoting sleep. In further experiments, compounds that activated GPR139 were reported to increase sleep duration and improve sleep quality in both mice and pigs.

The finding matters because many existing sleep medications can cause dependence or side effects such as next-day drowsiness or rebound insomnia. Medical Xpress noted that the results point to GPR139 as a possible drug target, but the evidence so far comes from animal studies. Further research would be needed to determine whether the same mechanism operates in humans and whether it can safely support new treatments for insomnia or other sleep disorders.