Lack of sleep. And i feel lethargic.

I have troubles falling asleep. First of all, my sleep is not at all peaceful. Even a slightest of disturbance, wakes me up. I am an active person. I dance alot and exercise regularly, still i am unable to sleep. I feel tired and sleepy at night, but when i try to sleep I can't. I have tried listening to calm music, done some affirmations and breathing exercises, yet it takes around 4-5 hrs to fall asleep and i wake up every 2 hrs which causes a sharp pain in my head. I feel as if I am half awake while sleeping. I have realised that a sound and peaceful sleep for 4-5 hrs is enough for me to survive a day, However i do not get this peaceful sleep due to which the whole day goes stressed and i feel lethargic.