All animals sleep, as do mammals, birds and some insects. However, how this basic function is regulated by the brain remains unclear.
According to a new study by researchers from the RIKEN Brain Science Institute, a brain region called the lateral habenula plays a central role in the regulation of REM sleep. In an article published today in the Journal of Neuroscience
, the team shows that the lateral habenula maintains and regulates REM sleep in rats through regulation of the serotonin system. This study is the first to show a role of the lateral habenula in linking serotonin metabolism and sleep.
The lateral habenula is a region of the brain known to regulate the metabolism of the neurotransmitter serotonin in the brain and play a key role in cognitive functions.
"Serotonin plays a central role in the pathophysiology of depression, however, it is not clear how abnormalities in regulation of serotonin metabolism in the brain lead to symptoms such as insomnia in depression," explain Dr. Hidenori Aizawa and Dr. Hitoshi Okamoto who led the study.
Since animals with increased serotonergic activity at the synapse experienced less REM sleep, the researchers hypothesized that the lateral habenula, which regulates serotonergic activity in the brain, must modulate the duration of REM sleep.