Over the past couple of years, Robert Stickgold, a cognitive neruoscientist at Harvard Medical School, has teamed up with Mathew Walker of Boston's Beth Israel Deaconess Medical Center to investigate sleep's effects on procedural memory for motor skills.

They asked right-handed test subjects to type a sequence of numbers with their left hand as fast as they could. No matter what time of day they learned the task, their accuracy improved 60% to 70% after six minutes of practice. When subjects who learned the sequence in the morning were retested 12 hours later, they didn't significantly improve. But when those who learned the sequence in the evening were retested following a night's sleep, they were 15% to 20% faster and 30% to 40% more accurate.

New technology is leading to more insights. Research by Bruce McNaughton, a psychologist and physiologist at the University of Arizona in Tucson, has shown that many of the same neurons that fire during the daytime -- say, when a rat is learning to navigate a maze -- are reactivated during the REM stage of sleep. "Basically, the brain is reviewing its recently stored data," McNaughton says. Eventually the brain consolidates those patterns.

Perhaps that's what sleep really is: repeated cycles that aloow you to learn new tricks without forgetting old ones

Gotcha. Sounds good. Even better would be to have an early morning or noon practice to do the work and then an evening session to refine and revise the work.

That is interesting, kbk. But I do wonder with relation to performance anxiety how that applies. Someone may have an emotional attachment to the piece their performing, but then they forget the piece because of the emotional reaction to performing for an audience. They are able to recall the piece afterward again, and their love of the piece hasn't changed, necessarily.

I have found that doing slow, deliberate, accurate play- throughs of material I learned that day and the day before that , before retiring for the night, has done wonders for my speed of learning and ability to memorize.

This study would seem to scientifically support my anecdotal findings.