“Power Sleep: How to Prepare Your Mind for Peak Performance” James Maas; Villard Books $25, 248 pages

If you think you can get by on less than eight hours’ sleep, you may want to read this book. According to James Maas, a Cornell University psychologist and leading sleep researcher, it’s the eighth hour of sleep that leads to peak performance. Maas’ research shows that the last stage of REM sleep, which typically occurs in the eighth hour, is the most restorative to the brain. Maas is aghast at Americans’ sleep habits--most adults get six to seven hours of sleep a night--and has stats to show what a sorry state we’re in. For example, the parents of a new baby lose 450 to 700 hours of sleep in the child’s first year of life. Maas also says that adolescents need far more sleep (about 10 hours) than they get (about six hours). The book helps readers assess their own sleep problems and provides instruction on how to develop healthy sleep habits.