Guest post by Con Iber, MD, Fairview Sleep Centers medical director
Your body may be idle while you sleep, but your brain is actually hard at work. The sleeping brain’s to-do list includes storing memories, improving motor functions, and even solving problems that may have stumped you throughout the day.
Thanks for the memories
After absorbing and processing information all day long, the brain uses sleep to store—and sometimes revise—the memories we’ve made during our waking hours. During sleep, our brains create synaptic connections for our experiences, turning them into long-term memories. Oftentimes, our brains create stronger connections for experiences to which we’ve had an emotional response.
We may well not remember what we viewed on our way to work unless, for instance, it involved witnessing an accident along the side of the road. We may not remember what we heard in class unless the teacher notes “this will be on the test.” Interestingly, once memories are stored, they are still open for subsequent revision—a fact that plays out in the occasional incorrectly recounted event.
During sleep, the brain also takes memories from the hippocampus (the center of emotion, memory, and the autonomic nervous system) and integrates them into our existing scaffold of knowledge in the cortex. This allows us to use those memories to improve our problem solving and motor tasks the next day.
As a result, when we wake we are more capable of solving problems and, in fact, we may well wake with the epiphany of having solved the problem we struggled with the night before with a triumphant morning “Aha!”
Sleep also restores connectivity to our emotional governor, the amygdala, so that we have a more balanced view of the world we experience. Because the brain is busy completing tasks every night, if we are not getting enough sleep we may well be shortchanged on what our brain is capable of doing the next day. Some of the consequences may be serious.
Toddlers who do not get enough sleep are often characterized as “cranky.” Adolescents getting less than five hours of sleep a day are much more likely to attempt suicide or have car accidents than those who get seven to nine hours of sleep.
Science has been uncovering the mystery of what sleep accomplishes for the brain over only the last two decades. Delve more deeply into the evidence with the sources below.