Sleep can help both learn a new piece of information, as well as get the brain to file it away for later retrieval. Sleep helps people remember a newly learned word and incorporate new vocabulary into their mental lexicon, according to researchers.
The study, conducted by researchers at the University of York and Harvard Medical School, has just been published in the Journal of Neuroscience.
Researchers taught volunteers new words in the evening, followed by an immediate test. They slept overnight in the laboratory while their brain activity was recorded using an electroencephalogram (EEG). A test the following morning revealed that they could remember more words than they did immediately after learning them, and they could recognise them faster demonstrating that sleep had strengthened the new memories.
This phenomenon, however, did not occur in a control group of volunteers who were trained in the morning and re-tested in the evening, with no sleep in between. The researchers also found that deep sleep (slow-wave sleep) rather than rapid eye movement (REM) sleep or light sleep helped in strengthening the new memories.
Co-author of the paper, Professor Gareth Gaskell, of the University of York’s Department of Psychology, said: "We suspected from previous work that sleep had a role to play in the reorganisation of new memories, but this is the first time we've really been able to observe it in action, and understand the importance of spindle activity in the process.”
Lead author, Dr Jakke Tamminen, said: “New memories are only really useful if you can connect them to information you already know. Imagine a game of chess, and being told that the rule governing the movement of a specific piece has just changed. That new information is only useful to you once you can modify your game strategy, the knowledge of how the other pieces move, and how to respond to your opponent’s moves. Our study identifies the brain activity during sleep that organises new memories and makes those vital connections with existing knowledge.”
