I'm Sarah Bernier Olin, a stress reduction and meditation expert. No need to wait for the so-called "zombie apocalypse" to hit. Many people are already living i hat's because when you don't get the recommended seven to eight hours of sleep a night -- maybe due to work or family stress, illness, and/or bad habits -- your may feel like a living version of the walking dead. Being drowsy or sluggish the next day isn't the worst side effect. When you lose precious shuteye, you may also lose some focus, alertness, and productivity. Take a cue from one of history's most influential figures, Albert Einstein, who was a power napper. A 20-minute afternoon nap -- whether it's on your living room sofa, laying your head on your desk behind closed office doors, or resting in your parked car -- a quick snooze might be just enough to help you feel more mentally and physically recharged the rest of the day. Don't sleep for longer than 20 minutes to avoid a feeling of post-nap grogginess that comes from waking up from a deep sleep. And if you are dealing with insomnia, talk to your health care provider about whether napping may make your condition worse. Remember that napping too late in the day can make it more difficult to fall asleep at night. Try a brief nap mid-day -- that's when it will feel like a mini vacation. Bon voyage -- I mean, sweet dreams!