A new compound named Suvorexant – based on  neurotransmitters called orexins – is in the pipeline. It is currently developped by Merck. The FDA have reviewed the product, and, according to my understanding, given partial approval, with the exception that the dosage suggestions/recommendations  should be revised and lower doses should be reinforced.

A statement  by Merck can be found here.

Comment: Many sleeping pills have a definite risk of abuse, drug tolerance and addiction.
Any new approach without these unwanted side effects or drugs that may be potentially helpful in patients with insomnia and who have failed to respond to current treatment, would be highly welcome.