Huge news for busy people, procrastinators and those who love to run in the moonlight: You can now work out before bed. Doctors and sleep experts (as well as your mom) previously recommended against this—the thinking was that the boost in adrenaline and heart rate would keep you awake. However, there wasn't a lot of solid evidence to support that theory. Then earlier this year, the National Sleep Foundation (NSF) found in a large survey that those who report exercising close to bedtime don't usually experience any differences in sleep quality
compared with those who exercise earlier in the day. In a striking reversal, the NSF deleted the "no sweat before bed" rule from its sleep hygiene recommendations and now advises that exercise at any time of the day
appears to be good for normal sleepers (chronic insomniacs might want to check with a specialist first). There's even evidence that light exercise—walking, yoga, Pilates, toning with weights—before bed can help
you sleep, says H. Craig Heller, a biology professor at the Stanford University School of Medicine. The activity makes you feel slightly warm, and if you then go into a chilled bedroom, the drop in body temp will put right you out.