Settling the Debate on Serotonin's Role in Sleep

Posted on June 28, 2019

Serotonin has been shown in some studies to help with sleeping, while other studies found that serotonin is often produced when an individual is awake. In order to determine the role of serotonin in sleep, scientists from Caltech focused on a region in the brain that has the most serotonin-producing neurons.

The study first involved zebrafish as experimental subjects as the zebrafish larvae have sleep cycles similar to those of humans. The fishes were then mutated such that the neurons no longer produce serotonin. A separate group of fishes had their serotonin-producing neurons removed completely. Results indicate that the mutated zebrafish had half the amount of sleep as normal zebrafish. When the serotonin-producing neurons were removed, the fishes also slept lesser than normal.

This shows that serotonin is important for normal amounts of sleep in zebrafish. Another experiment was carried out, this time modifying the brain region producing serotonin such that it can be activated by light. Exposing the modified zebrafish to lights causes them to fall asleep, suggesting that activation in the particular brain region leads to sleep. The research was furthered using mice as subjects, resulting in the similar findings.

Two factors are involved in inducing sleep. The first factor is the circadian clock, where the body is awake during the day when it is bright, and when night falls, the body will start to feel sleepy. The second factor is the homeostatic sleep pressure, which builds up throughout the day when the individual is awake. For sleep to occur, there should be high sleep pressure and the circadian clock has to be aligned with the timing of the day.

Therefore, it is suggested by researchers that the release of serotonin contributes to sleep pressure. This was supported by the fact that the animal subjects experienced lower sleep pressure when less serotonin was available. While these findings were obtained from animals, the serotonin production system that these animals possess are similar to those of humans, which can help us understand the role of sleep in humans.

Category(s):Other, Sleep Disorders

Source material from Science Daily