Take a hot shower or bath before going to bed.

Take a warm shower or bath, preferably one or two hours before bedtime. You can also try adding some lavender oil to your bath. It's a proven classic that helps you relax and fall asleep more easily. 

WHY IT HELPS:
The warm water actually causes the body's core temperature to drop. This is because blood is drawn from the inner parts of the body to the outer layers. The drop in body temperature can make you feel sleepy, helping you to relax and unwind.