You're suffering from Insomnia. Some people are constantly affected by insomnia while others are only affected by insomnia every now and then.
I don't recommend taking sleeping pills but in some cases you might have to take them once in awhile when you can't drift off to sleep on your own.
But another natural thing you can try is drinking some warm milk if you're not allergic to milk.
I don't know what it is but warm milk is a very good sedative for some people.
Also try avoiding any electronics an hour before bed. The light from tv screens, computer screens and other electronics messes with our natural body clock.
Try going to sleep at the same time each night as well this helps to keep your internal body clock in time.
Going to bed at different times messes up our body clock.