Merck's ($MRK) long-awaited insomnia drug Belsomra (suvorexant) has now hit pharmacy shelves in the U.S. The drug is a first-in-class sleep aid finally approved last year after an initial rejection by the FDA. Early analyst estimates had put 2017 sales at more than $500 million, but after the agency chose to approve a lower dose than hoped for, those forecasts fell to about $300 million. Release