Sonata: Of all the new sleeping pills, Sonata has shortest half-life, which is the amount of time it takes for half of the drug to be eliminated from your body. Its half-life ranges between 30 and 60 minutes. That means you can try to fall asleep on your own. Then, if you're still staring at the clock at 2 a.m., you can take it without feeling drowsy in the morning.
Ambien: The most commonly prescribed sleeping pill, Ambien has a moderate half-life of less than two-and-a-half hours. This means that Ambien is great for helping you get to sleep but, like Sonata, could be less helpful if your problem is waking up wide-eyed in the wee hours.
Ambien CR: Ambien CR, approved by the FDA in 2005, was designed to target both common sleep problems: difficulty falling asleep and difficulty staying that way.Think of it as a layer cake: one layer dissolves quickly to help you fall asleep, while the second layer dissolves more slowly to help you stay asleep. Clinical trials showed that Ambien CR decreased wake time after sleep onset for the first seven hours during the first two nights it was taken, and for the first five hours after two weeks of treatment.
Lunesta: Of all the newer sleeping pills approved so far, Lunesta has the longest half-life -- about six hours. This means you may feel groggy in the morning if you take it in the middle of the night, or at a time when you can't get a full night's sleep. On the other hand, this pill could help you if you tend to wake up in the middle of the night a lot. Lunesta is approved by the FDA for long-term use and has been found to help menopausal women sleep through the night.
Benzodiazepines: These older sleeping pills, which include drugs like Valium and Halcion, are useful when you want a drug that stays in your system longer. For instance, they have been effectively used to treat sleep problems such as sleepwalking and night terrors, says Arand. "The biggest problem with these is daytime sleepiness, although you also have to monitor them more closely for dependence as well," she says. (Dependence means that you always need the drug to go to sleep.)