They found that the people who pictured relaxing scenes fell asleep 20 minutes than they did on nights where they counted sheep. The scientists believe that counting sheep is just too boring to do for a long time and may even add to anxiety (imagine counting the 200th sheep!).[h3]How to Fall Asleep[/h3] If you are looking for a replacement method (since counting sheep doesn't seem to work), try this 4 week program to Fall Asleep Faster. It'll give you one task per week to prime your body for a great night's sleep.
Source: Behav Res Ther. 2002 Mar;40(3):267-77. The management of unwanted pre-sleep thoughts in insomnia: distraction with imagery versus general distraction. Harvey AG, Payne S.