Sleep needed to downscale the brain’s synapses

Chiara Cirelli: We all know that we need to sleep, because when we wake up and feel refreshed we have the proof that sleep is doing something very important.

That’s sleep expert Chiara Cirelli of the University of Wisconsin. She believes we need sleep to refresh our synapses, which connect brain cells.

Chiara Cirelli: If you do not downscale synapses, the next day synapses are already too strong, too big, and are basically saturated in their ability to learn. So going to sleep will allow you to downscale synapses in such a way that the next day you are fresh and ready to learn again. Though all animals need sleep, Cirelli said, they don’t all sleep in the same way.

Chiara Cirelli: Since different species – insects, fish, rodents – sleep different ways because they have a different brain anatomy, it suggests that perhaps the common ground that mediates the sleep function is at the cellular level.

But, Cirelli added, observing changes in brain cells – between sleeping and waking, in a living animal, in real time – is still a technical challenge. Cirelli said that most experts agree that sleep is also important for memory, although they disagree about why it’s important.

Chiari Cirelli: What we are trying to understand is the mechanism by which sleep can benefit memory. Some people think that it’s through an active replaying and strengthening of the connections and synapses that have been used during learning in waking, while instead we think that the benefit comes from the generalized downscaling.

Our thanks to:
Chiari Cirelli
Associate Professor of Psychiatry
University of Wisconsin, Madison