Rozerem: Pros and Cons of the Newest Prescription Sleep Aid

But in clinical trials Rozerem still caused side effects, such as daytime sleepiness and dizziness, in a small percentage of people. It has also been associated with altered hormonal levels, which may cause sexual side effects. Rozerem has not been studied in patients with sleep apnea or related breathing disorders.

The real question about Rozerem, though, is how well it works. In a 2006 government-sponsored analysis, it performed slightly worse than hypnotic medications; patients fell asleep seven to 16 minutes faster and slept 11 to 19 minutes longer than they did with a placebo.

Rozerem, like its over-the-counter relative, melatonin, works as a chronobiotic, explains Matthew Ebben, PhD, a sleep specialist at the Weill Cornell Medical College. "It may work for someone who needs to have their circadian rhythms shifted—if someone's internal clock got messed up because of jet lag, and they want to sleep at all the wrong times, for example," he says.

"It's also being studied in blind people who lack the environmental cues—light and dark—that the body uses to naturally transition into sleep. But for people who just aren't sleepy at all, traditional insomniacs, it's unclear whether Rozerem really makes much of a difference."

One benefit of Rozerem over OTC melatonin: The prescription medication is held to high standards in terms of ingredients and strength of the product, whereas supplements are not regulated by the FDA and there's no way to verify their contents.