Earlier this year, Merck (nyse: MRK - news - people ) licensed a sleeping pill from Lundbeck, a Danish drug firm.

FORBES: Sleep On Demand

In the past three months the FDA has slapped cautionary labels on sleeping pills and yanked Novartis (nyse: NVS - news - people )' constipation drug Zelnorm after that company's analysis showed heart problems.

FORBES: Lynch 'Em

The last big shift in the sleeping-pill market came 12 years ago, when Ambien hit pharmacy shelves in the U.S. The drug is viewed as having fewer side effects than older sleep aids such as Halcion, which left patients feeling groggy in the morning.

FORBES: Magazine Article