The two main phases — non-REM and REM sleep — also differ vastly in terms of physiology. During NREM sleep, your muscles relax and your heart rate and breathing slow down. You’ve spiraled down into a very deep sleep. In REM sleep, there is rolling of the eyes and fluttering of the hands. NREM is often characterized as involving an inactive brain and active body, while REM involves an active brain and an inactive body.
During REM sleep, the brain is not only in a state of heightened activity, it is also no longer governed by the regions that control logic and inhibit impulses. Unconstrained by reality, fragments are loosened from their original context and recombined in strange, exhilarating, and sometimes frightening ways. It is all very vivid and emotionally intense, as the unbelievable becomes believable.
“In REM sleep the neocortex replays abstracted knowledge in much more random combinations than during slow wave sleep,” says Lewis. The brain also releases an important chemical called acetylcholine. This is an essential neurotransmitter that disrupts communication between brain cells, limiting their ability to transmit information to each other.
“During slow wave sleep there’s a strong connection between the hippocampus and the neocortex, but during REM sleep that connection is inhibited by acetylcholine. So instead of working together, they work independently,” says Lewis. Unfettered by existing connections, each is free to create new ones. They can make new links between neurons or disrupt old ones.
The first phase of REM sleep occurs about 90 minutes after you fall asleep and lasts up to 20 minutes. As the sequences of NREM and REM sleep alternate with each other, each subsequent cycle of REM sleep gets longer. During an eight-hour period of sleep, your brain cycles back and forth about five or six times.
Scientists are still debating whether NREM sleep or REM sleep is more important for creative problem-solving. But Lewis suggests they build on each other as the brain cycles between the two several times over the course of a night. One could compare it to two musicians who want to perform a duet together. Each goes off to practice his or her part alone and then they meet again to play the finished piece. Over time, through a process of rehearsal and performance, they would continue to improve their mastery of the score.
Because the effect grows stronger, it could mean that the brain’s ability to solve a given problem also increases with each night of sleep.
Do Dreams Serve A Purpose?
Once scientists began exploring REM sleep, research into dreaming took off. Dreams have fascinated scientists, artists, and philosophers for centuries. Some have claimed that dreams bear messages from beyond or that the symbols they contain provide clues to future events. To this day, nobody really knows where the content of our dreams comes from or what purpose they serve, if any.
Many sleep experts consider dreams to be nothing more than chance events occurring in the brain which are devoid of any real meaning. In spite of their potent emotional force, dreams are merely the result of the random firing of neurons. It is only after we wake that the brain, seeking order, weaves the pieces together in search of some significance.
But not all scientists agree. Some sleep researchers suggest that, in fact, dreams form a crucial part of memory processing. As Dr. Robert Stickgold, Ph.D., at Harvard University Medical School writes, “Dreaming of recent experience reflects the reactivation and consolidation of memory in the sleeping brain.” In his view, the purpose of dreaming is to determine what new information is useful and to help the brain make predictions about the future.
Dreams are difficult to study scientifically, though, because the activity is too deep within the brain for observation. Sleep researchers mostly rely on people’s dream journals and self-reports. Newer technology allows researchers to monitor the brain more closely. This allows scientists to trace what is happening physically and chemically and to use that information to form inferences.
Although these theories still need to be tested, researchers are moving one step closer to uncovering the link between sleep, dreams, and creativity.
So the next time you’re up late dealing with a difficult problem, don’t worry about feeling drowsy. Getting some decent sleep could be good for your creativity.
