a bed with a colorful blanketEveryone agrees that sleep is important, but a new study claims that sleep’s benefits are not what people think they are. Researchers from the University of Wisconsin School of Medicine and Public Health articulated a theory that sleep is important because it weakens brain cell connections. The researchers’ SHY (synaptic homeostasis) hypothesis is in contrast to other sleep science, which has asserted that sleep strengthens brain connections.

Using a battery of tests, the research team, comprised of psychology professors, Dr. Giulio Tononi and Dr. Chiara Cirella, constructed their theory of synaptic homeostasis. They conducted laboratory studies on animals as simple as fruit flies and complex as humans. They also used sleep studies and computer simulations to compile data about what happens during sleep on molecular, electrophysical, and behavioral levels.

The result was the SHY hypothesis. This hypothesis asserts that sleep weakens brain connections so that the brain can rest and maintain a balance. During the day, humans learn, which strengthens neural connections. Tononi and Cirella’s hypothesis is that the brain needs time to stabilize and prepare for new learning the next day. If the brain’s connections continued to strengthen at night, they would interfere with learning tomorrow’s new skills.

This “smart forgetting” allows the brain to eliminate useless details, clearing space for the important memory work like acquisition and consolidation. In essence, sleep, by balancing out the brain, enables continual learning.

“Sleep helps the brain renormalize synaptic strength based on a comprehensive sampling of its overall knowledge of the environment, rather than being biased by the particular inputs of a particular waking day,” explained Tononi

This research is published in the journal Neuron.

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