Daytime nap 'is as refreshing as a night's sleep' By David Derbyshire Filed: 23/06/2003 Power naps, the post lunch snoozes advocated by Winston Churchill, Albert Einstein and George W Bush, can be as refreshing as a good night's sleep, according to a study. Scientists have shown that a 60- to 90-minute siesta can charge up the brain's batteries as much as eight hours tucked up in bed. But in order to get the full benefit, dozers need to spend some of that time dreaming, the study found. The findings come from psychologists at Harvard University, who tested the visual learning...