The neurotransmitter dopamine is responsible for switching the mouse brain between the two main modes of sleep: rapid eye movement (REM) sleep and non-REM sleep.
In all animals, sleep alternates between REM sleep, which is associated with dreams and memory consolidation, and non-REM sleep. But it hadn’t been clear what causes the brain to switch between these two modes.
Now, a team led by researchers from the University of Tsukuba in Japan has shown that temporary blips in dopamine levels in the basolateral amygdala, a region of the brain associated with emotion, flips the switch between the two sleeping modes in mice.
The researchers were able to induce mice to go from non-REM to REM sleep by artificially activating dopamine-receptor-expressing neurons in this region.
This finding will help inform research into sleep disorders such as narcolepsy, which is characterized by sudden sleep attacks.