Intellect thrives on sleep

Land of nod is a learning experience

Cramming all night might help you to scrape through exams, but it won’t make you clever in the long run. Human and animal experiments are lending new support to a common parental adage: that a good night’s sleep is essential to learning.

“Modern life’s erosion of sleep time could be seriously short-changing our education potential,” warned Robert Stickgold of the Massachusetts Institute of Technology at the meeting of American Association for the Advancement of Science in Boston this week.

Many pianists find that sleeping on a tune can help their performance. Similarly, in the lab, volunteers’ skill at key-tapping and speed-spotting tasks improved by 20 per cent with one nights’ sleep after training. Extra nights of slumber enhanced skills even more.

If robbed of the first night’s kip, however, subjects went back to being novices – even two days later after catching up on their shut-eye. “How well you do at some things depends not on where you went to school or what your parents do, just on how well you slept last night,” said Stickgold.

He and his team have also found that different sleep phases influence different types of learning. Acing a visual test requires relaxed slow-wave sleep in the first quarter of the night, and rapid eye movement (REM) sleep in the last quarter. A movement test such as key tapping relies more on the non-REM episodes in the later part of the night.

“I think sleep is involved in rehearsing, restructuring and reclassifying our existing world view to allow us to function better,” Stickgold said.

Catnap dreams

As pet owners have long suspected, the same may apply to animals. Daniel Margoliash of University of Chicago has found evidence that young birds rehearse their new songs while sleeping. The brain cells that fire when birds make their first faltering efforts at singing show similar activity when they nap. “Birds dream of singing,” says Margoliash.

Rats, meanwhile, rehearse running in their sleep. After navigating a spiral maze all day, the rodents’ brains replay electrical signals that are characteristic of the motion throughout the night, Matthew Wilson of the Massachusetts Institute of Technology, told the meeting.

“Just like our own dreams, the replay can be recognisable but warped; some events are stretched out over time and others never really happened,” said Wilson. He believes that new experiences are generalized and re-evaluated during sleep.