Two experiments primed college students with either sleep-related or neutral words and then assessed sleep during a 25 minute nap period. Both experiments showed that participants primed with sleep-related words reported having slept longer than did those primed with neutral words. Furthermore, both experiments showed that sleep-primed participants exhibited lower heart rate. Experiment 2 also revealed that the effect of the priming manipulation was especially strong among participants who had trouble sleeping. This suggests that priming might be a cost-effective treatment for inducing sleep among people with sleep problems.

http://onlinelibrary.wiley.com/doi/10.1111/jasp.12123/abstract

You do the priming by writing words like relax, comfy, warm, etc where you can read them from bed