Dream Stage of Sleep May be Essential to Learning New Skills
Oct. 27, 1992
LOS ANGELES (AP) _ People who dream during a good night's sleep are more likely to remember newly learned skills, a researcher said Tuesday.
''For some types of problem solving, one should consider not only 'sleeping on it,' as common wisdom would have it, but perhaps 'dreaming on it' as well,'' Israel's Weizmann Institute of Science said in a news release describing the research.
Dr. Avi Karni, an institute neuroscientist, said his study shows the dream stage of sleep - called REM or rapid eye movement sleep - helps people permanently remember skills they were taught hours earlier. People deprived of REM sleep have trouble remembering new skills, he added.
The findings suggest that ''how to'' skills such as how to read, type, fly a plane or perform other tasks might be taught most effectively during afternoon or evening hours before a good night's sleep, Karni said.
He said the study also indicates that drugs or other methods might be developed to improve skill learning by increasing the length of the REM sleep.
Karni, who is doing postdoctoral research at the National Institutes of Health in Bethesda, Md., presented his findings in Anaheim during the annual meeting of the Society for Neuroscience.
''This work may be some of the best in a decade'' in the field, said psychologist Bela Julesz, head of vision research at Rutgers University.
Karni's study is ''remarkable'' because it also showed that a critical phase of learning new skills happens at a very basic level: where nerve cells in the brain's visual cortex first receive signals from the eyes, Julesz said by phone from New Brunswick, N.J.
The study provides clues about how, when and where in the brain a learned skill is ''imprinted'' in memory, Karni said.
''It's a great study,'' said psychologist Carlyle Smith, of Canada's Trent University in Peterborough, Ontario.
Smith conducted previous research showing that students who study hard during weekdays forget much of what they learned if they disrupt their REM sleep by partying all night on weekends.
Karni and Smith said their studies show dream sleep is important only for memorizing ''how to'' skills, not for memorizing factual or ''what'' knowledge, such as the contents of a book.
Karni conducted his study with neuroscientist Dov Sagi and others at the Weizmann Institute in Rehovot, Israel, and the Sheba Sleep Laboratory outside Tel Aviv.
Four volunteers were trained to quickly recognize a horizontal or vertical bar embedded in a computer screen covered mostly by horizontal lines. As the screen flashed 1,000 new patterns during a 20-minute training session, the observers had to quickly say which bar pattern they saw.
Their accuracy was tested right after a training session, then again the next morning. During the intervening nights, the observers' brain waves, eye movements and muscle activity were monitored as they slept. On some nights they slept normally; on others they were awakened by a loud bell during different stages of sleep.
Their performance improved sharply after a good night's sleep, indicating that learning a skill is a multi-hour process that requires sleep. However, their performance didn't improve by the next morning if they were awakened during REM sleep. Disruption of other sleep stages didn't impair performance, meaning that only dream sleep is important in permanently memorizing a new skill.
Karni believes REM sleep is essential to learning skills because memories can be stored more efficiently during sleep than when a person is awake and bombarded with information.