L._.
That night the king could not sleep; so he ordered the book of the chronicles, the record of his reign, to be brought in and read to him. Ester 6:1
I believe the best way to learn to sleep is to study the word at night. Read it, pray about it, and let the Lord give you that sleep you need. He probably wants to spend time with you. But once you begin doing that on a regular basis, he will heal your sleep problems.