A good night's sleep contributes to your well-being as much as good food and exercise. But how many hours of sleep do you actually need to get yourself through the day comfortably and maybe even with energy to spare? On your next vacation, try going to bed at the same time every night, then waking up without an alarm clock. If you feel fully rested after a few days, that's the amount of sleep you should aim for on a daily basis. Happy dreams!