Sleep restores lost memories

A memory lost during the day can be recovered after a few hours sleep, say scientists.

Researchers at the University of Chicago say sleeping enables the brain to recover lost memories and appears to be essential for remembering names, telephone numbers and where you put the keys.

They found that people improved at memory experiments after a good night's sleep. In the journal Nature, the scientists, Kimberly Fenn, Howard Nusbaum and Daniel Margoliash, say: "Sleep consolidates memories, protecting them against subsequent interference or decay. Sleep also appears to 'recover' or restore memories."

Their study involved testing students who were asked to recognise the words spoken by a voice synthesiser which involved learning and remembering unusual speech patterns. Most remarkable was the loss of learning the students experienced during the day and then recovered.