In an article I found called How Deep Sleep Clear’s a Mouse’s Mind, Literally, I learned about the process of cleaning waste out of the brain during deep sleep. Waste could include toxic waste that turns into plaque that sticks onto the brain and could cause neurological disorders. This process is called the glymphatic system. The glymphatic system sends out fluids from the brain and spinal cord called cerebrospinal fluid to flush out the waste.
In order to figure out the main factor that drives this system, Danish scientists conducted an experiment in which they studied the deep sleep of mice, and gave some of them a common drug called zolpidem to fall asleep and the others nothing. They discovered that there is a molecule called norepinephrine which is released in waves during sleep. The waves correspond to blood volume, so blood volume fluctuates depending on these waves. Therefore, a pulsing in the blood vessels occurs. Furthermore, they found that the flow of cerebrospinal fluid corresponds to blood volume as well, which causes the blood vessels to then pump out the fluids into the brain to remove the brain waste.
The scientists then wanted to discover if this process is exactly the same in all sleeps, which is where the sleeping drug zolpidem comes in. In this portion of the experiment, they discovered that norepinephrine waves were 50% less frequent and that the release of fluids into the brain dropped more than 30% in the mice that were given zolpidem, even though they fell asleep faster. Therefore, drugs that help with sleep cause less waste clearance to occur in the brain.
It was interesting to me how they could conduct these experiments on animals as little as mice in order to discover what happens in our own human brains. I wouldn’t have known that mice’s brains are similar enough to ours that the same exact processes happen in both.
Article: https://www.sciencedaily.com/releases/2025/01/250108143735.htm
