There’s no need to fight off that bout of fatigue in the middle of the day. When Harvard University experts studied 24,000 subjects, they found that for both men and women, taking a nap in the middle of the day—even for just 30 minutes—slashed mortality risk by as much as one-third. And for more ways to stay well-rested, check out these 20 Nighttime Habits That Guarantee a Full Night’s Sleep.