There's nothing magic about the  number eight, more sleep may not always be healthier, but you can't function on four hours of sleep. 

You May Not Need Eight Hours - NYU Psychologist Joyce Walsleben, Ph. D., everyone has different sleep needs and you will know if you're getting enough when you don't feel like falling asleep in your afternoon sales projection meeting.

More Sleep Isn't Always Healthier - According to Dr. Najib Ayas of the University of British Columbia, some studies have found that people who slept longer than eight hours died younger than those who slept between six to eight hours. What isn't clear just yet is if sleeping long is a symptom of poor health or a cause of it. Long sleepers may suffer from sleep apnea, diabetes or depression that causes them to spend more time in bed.

You Can't Function on Four Hours of Sleep - Thomas Roth, Ph. D., a sleep researcher at Henry Ford Hospital in Detroit says that "short sleepers" just aren't aware of how tired they really are. Roth says that not enough sleep is bad for your health and your image. It can be a contributor to poor judgment, inability to pay attention and it also weakens your immune system.

Waking Up During the Night Means You're Tired All Day - It just may be your natural sleep cycle. Dr. Thomas Wehr at the National Institute of Mental Health says that he conducted a study with 15 people who slept without artificial lights for a few weeks they slept better and said they never felt so rested.

You Need Drugs to Sleep - Not so says Dr. Daniel Kripke with the University of California San Diego. Sleep meds are designed to treat short term sleep issues caused by life changes and stressful situations. People who have longer term problems won't really benefit from meds. The good Doctor says that people who have long term sleep issues will benefit more from behavior modification such as going to bed at the same time every night, avoid computers or phones right before bedtime, turn off the TV, and knock it off with the caffeine six hours before you go to sleep. Dr. Kripke says, "People who think that they have insomnia actually may have anxiety or depression."

You Can Make Up Lost Sleep on the Weekend - Overdoing it on sleep on the weekend upsets your circadian rhythms and makes it harder to get refreshing sleep that your body needs. Robert Stickgold, Ph. D., of Harvard calls weekend sleep binging "sleep bulimia". Sleeping until noon on Sundays prevents you from going to bed at your normal time to get enough sleep to be bright eyed and bushy tailed for Monday morning. Sleep experts say it's best to get up at the same time every day, including weekends.

Tylenol PM is Best for Occasional Sleep Issues - If the sleeplessness lasts longer than a few nights, it's not a good idea to take it. Dr. Helene Emsellem of the Center for Sleep & Wake Disorders says that "Tylenol PM is no better than a prescription drug for people who have trouble falling asleep and may be less effective than some prescription drugs." The active ingredient in Tylenol PM is an anti-histamine and its side effect is drowsiness and some people who take it have reported a "hung over" feeling. If you do take a sleep aid with an anti-histamine in it like Nytol, Unisom or Benadryl, give yourself at least 8 hours for it to work.