Posts Tagged ‘Sleep’

Keep Forgetting? Remember to Sleep!

April 26, 2009

Dimitri Mendeleev Came Up With Periodical Table During a Dream

Dimitri Mendeleev Came Up With Periodical Table During a Dream

The joke goes, writes Robert Stickgold, associate professor of psychiatry at Harvard Medical School, that everyone knew memory and sleep were related except for the people who studied memory and the people who studied sleep.

Writing in the April 27, 2009 issue of Newsweek,  Stickgold says that the relationship is now very clear, even if we don’t know which way all the causation arrows are pointing. Consider this:

  • In tests of the different kinds of memory… procedural, declarative, episodic… ‘sleeping on it’ after first learning the task almost always improves performance.
  • Sleep deprivation experiments makes memory acquisition harder. And, the tired brain has a harder time still capturing positive memories than negative ones. That could be why sleep deprivation is so often associated with depression.
  • The two memory systems, the hippocampus and the neocortex, seem to interact during sleep. Increasingly it looks like that memory between the two systems is consolidated during sleep.
  • Not only memory, but connections between stored memories seem to take place during sleep. Dimitri Mendeleev (see above) fell asleep at his desk and dreamed up the Periodic Table of Elements during his slumber, for instance.

The Mendeleev anecdote has been underscored by modern research. German scientists gave game players a puzzle to solve involving seven calculations. Those that slept between game sessions were three times as likely to discover that the second calculation and the seventh gave the same answer.

Why does all this matter? Stickgold writes that some sleep researchers posit that for every two waking hours we need one hour of sleep to sort through what we’ve learned and experienced. For some people who get less than that it seems to lead to conditions like depression and post traumatic stress disorder.

The third of our life we spend  sleeping is rest for the body, but the brain remains active. “And much of that activity helps the brain to learn, to remember and to make connections,” Stickgold writes.

Not so sure? Then sleep on it and comment below.