One vital function of sleep may be to help our brains sort, store and consolidate new memories, etching experiences more indelibly into the brain's biochemical archives.
Even a 90-minute nap can significantly improve our ability to master new motor skills and strengthen our memories of what we learn, researchers at the University of Haifa in Israel reported last month in Nature Neuroscience. "Napping is as effective as a night's sleep," said psychologist Sara Mednick at the University of California in San Diego.
The expectation of a nap is by itself enough to measurably lower our blood pressure, researchers at the Liverpool John Moores University in England reported in October in the Journal of Applied Physiology. Indeed, regular nappers--working men who took a siesta for 30 minutes or more at least three times a week--had a 64% lower risk of heart-related death, researchers at the University of Athens reported last February in the Archives of Internal Medicine.
Moreover, slumber seems to boost our ability to make sense of new knowledge by allowing the brain to detect connections between things we learn. In research published last April in the Proceedings of the National Academy of Sciences, Dr. Matthew Walker of the University of California, Berkeley and his collaborators at the Harvard Medical School tested 56 college students and found that their ability to discern the big picture in disparate pieces of information improved measurably after the brain could, during a night's sleep, mull things over.
It is these patterns of meaning--the distilled essence of knowledge--that we remember so well. "Sleep helps stabilize memory," said neurologist Jeffery Ellenbogen, director of the sleep medicine program at Massachusetts General Hospital.
Source: Science Journal, The Wall Street Journal, January 18, 2008