This is common and tough at first.....

1)You need to get physical exercise and mental exercise without overdoing either.
-If your body does not move enough it will not tire out.
-If your mind does not exercise enough it will be active at night as well.

2) Too much heavy food(meats, sugars, refined foods) late at night will interfere as well too.

3) Herbs will help restore balance: Chamomile, Catmint, Lemon Balm, Passion Flower, Scullcap, Feverfew, Valerian Root, St. Johns Wort
*** if taking prescriptions, clear with your doctor AND pharmacist first.

4) A balanced diet high in vegetables and fruits is needed by the body to produce normal hormone levels and balanced bodily functions.

5) Melatonin 3-5MG hour before sleeping or trying to sleep.
This is a hormone which is naturally made by the body to induce sleep, you are lacking in it. It is made by a conversion of serotonin to melatonin, so you likely are low in serotonin too.

6) Too much mental stimulation will keep you up as well. Too much excitement, too much drama, too much TV, too much thinking or too much worry all keep the neurons firing.
Daily meditation practice too replace other stimulating activities will help correct this.