We ran a small RCT of MBSR versus eszopiclone (Lunesta) for people with chronic primary insomnia. http://www.ncbi.nlm.nih.gov/pubmed/21397868 There are other good trials of mindfulness interventions with sleep as an outcome in cancer, organ transplantation, and other populations.
You might also want to look at recent papers by Jason Ong (MBCT for insomnia), Sheila Garland (Mindfulness and sleep in cancer), and Cynthia Gross (transplant, chronic primary insomnia, MBSR, sleep).