While sleep issues are complex and evade a simple fix, there is a yoga technique which many have found to be very useful. It's a combination of conscious release breathing while focusing on ten points of the body - the two heels, the two buttocks, two shoulder blades, two elbows and two points on the back of the head. Here's how it's done:
While lying down bring your attention to the two heels instructing them "release and relax. Then move up toward the two buttocks instructing them to release and relax. Then the two elbows instructing them to release and relax. Finally, the two points on the back of the head instructing "release and relax".
Cycle through until you drift off.