The findings are reported by Quan Yuan, William Joiner, and Amita Sehgal at the University of Pennsylvania, and appear in the June 6th issue of Current Biology.
The fruit fly, Drosophila melanogaster, is now established as a useful model for sleep research. The simple nervous system of the fly enables researchers to ask basic questions about sleep regulation and function that have been difficult to address in the more complicated mammalian systems.
Using the fly model in their new study, the researchers showed that pharmacological treatment with serotonin increases the amount, as well as the quality, of sleep. Serotonin even improves sleep in certain mutant flies that normally sleep less or have fragmented sleep, suggesting that serotonin treatment can overcome some deficits caused by other sleep problems. The researchers also identified a serotonin receptor that affects sleep, and showed that it acts in a specific region of the fly brain known as the mushroom bodies. Interestingly, the mushroom bodies are required for learning and memory in flies. Given that consolidation of memory is one of the functions hypothesized for sleep, and that serotonin is known to be involved in learning and memory in other animals, it is possible that the effect of serotonin on sleep is related to its role in learning and memory.