Experts uncovered mechanisms that made new memory connections between brain cells while we sleep.
We know sleep plays an important role in memory and learning. But what actually happens inside the brain has been a source of puzzlement.
Two groups of researchers at New York University and Peking University used a microscope to look inside the living brain of mice to see what happened when they were either sleeping or sleep deprived. The sleeping mice formed significantly more new connections between neurons, showing they were learning more.
By disrupting specific phases of sleep in the mice, the research group showed deep or slow-wave sleep was necessary for memory formation. During this stage, the brain replayed the activity from earlier in the day. Sleep promotes new connections between neurons.
When sleeping, the brain is not quiet, it is replaying what happened during the day.
Last year, experiments showed the brain used sleep to wash away waste toxins built up during a hard day's thinking.
Another study discovered that napping improves your memory, reaction time, and productivity.
I'd been concerned over my short naps during the day. As soon as I relax in front of television with my feet raised, I nod off. This happens about twice a day. When I read last year that one of the oldest people in the world said she always took a nap, I felt reassured. Now, it's been discovered that people who nap live longer. And, conversely, those who are sleep deprived die early.
In the 1980s, a scientist from the University of Chicago conducted perhaps the best-known, and most disturbing, study into the topic.
He and his colleagues wired up a group of rats to a machine that measured their brain activity, and then placed each of the animals on a stationary disc above a bowl of water. Every time a rat’s brain activity indicated that the animal had fallen asleep, the disc would slowly rotate. This, in turn, forced the rat to wake up.
Despite having access to more than enough food, within a week these sleep-deprived rats started to lose weight and their fur developed an unhealthy yellowish tinge.
After a month, all of them had died, thus proving that sleep is essential for life. Read more here.
Volunteers who obtained nine hours’ sleep each night remained highly alert, while those spending just three or five hours in bed quickly became tired and inattentive.
However, the results from those getting seven hours’ sleep per night proved especially surprising. After just a couple of days they became significantly less alert, and remained sluggish for the remainder of the experiment.
So much for the old belief of seven hours sleep being ideal. I wake up refreshed and bright after about eight and a half hours. I've always been a good sleeper. I know now I'm one of the lucky individuals. So many other people fail to sleep well, my husband among them. How about you?