Our Brains Shrink While We Sleep

Recent studies have shown that our brains “shrink” while we sleep. During sleep, the brain’s synapses, or the connections among neurons, shrink by nearly 20 percent, allowing them to get some rest too and prepare for another day of learning.

This reset is known as “synaptic homeostasis,” and prevents synapses from becoming overloaded and burned out after a long day, allowing the brain and the body to recharge.

Dr. Chiara Cirelli of the University of Wisconsin-Madison Center for Sleep and Consciousness, and her colleague, Dr. Guilio Tononi, introduced the synaptic homeostasis hypothesis in 2003 and have since conducted studies on mice that proved their theory.

The research gives an answer to the age-old question: what is the purpose of sleep?

Humans have long suspected that our bodies required sleep in order to recover from the day, an idea that is not too far off from what the Cirelli and Tononi are suggesting. They explain that sleep plays a role in the growth of synapses, which are constantly growing to allow the flow of information to the brain as we take in new experiences.

However, that strengthening cannot go on forever and the body utilizes sleep time, when there is less information to process, to prune and rest the synapses.