If you can't remember a piano scale, don't think you're a musical dud. Instead, try getting a good night's sleep. That's what two sleep studies suggest. Researchers at the Weizman Institute in Israel say sleep is a key ingredient in improving skills learned by repetition, like playing a musical instrument. A separate study by scientists at the University of Arizona in Tucson found that brain-cell activity in sleeping rats may help strengthen the animals' memories of places they visited when awake.