I usually only sleep 3or 4 hours a night otherwise I live an extremely healthy life style. Are there some people who can get by with this?

Do you feel rested? For some individuals 3-4 hours is adequate. Two questions: 1) do you feel rested upon awakening, or are you tired during the day? 2) have you always slept 3-4 hours/night, and is there anything that impedes your sleep (ie, medical condition, insomnia, work/stress)? if your answer is "yes" it might be worth investigating further. Lack of good sleep can undermine your other good health habits.