Over the years, scientists have
come up with a lot of ideas about why we sleep. Some have argued that it’s a
way to save energy. Others have suggested that slumber provides an opportunity
to clear away the brain’s cellular waste. Still others have proposed that sleep
simply forces animals to lie still, letting them hide from predators. A pair of
papers published on Thursday in the journal Science offer evidence for another
notion: We sleep to forget some of the things we learn each day.
In order to learn, we have to
grow connections, or synapses, between the neurons in our brains. These
connections enable neurons to send signals to one another quickly and
efficiently. We store new memories in these networks. In 2003, biologists at
the University of Wisconsin-Madison, proposed that synapses grew so exuberantly
during the day that our brain circuits got noisy. When we sleep, the scientists
argued, our brains pare back the connections to lift the signal over the noise.
More information: