Here is a good article by Leslie Peters. She is a certified intermediate Iyengar Yoga teacher and the former director of the Iyengar Yoga Institute of Los Angeles. She is featured in the book Yoga: The Path to Holistic Health, by B.K.S. Iyengar.
Many things, such as stress, hormonal changes, medical or emotional problems, and certain medications, can cause insomnia. While there is no blanket solution to this complex and highly individualized problem, the practice of yoga can be helpful. If you are looking to yoga for serenity, here are some poses that will quiet and calm you.