Using noise for a good night's sleep.(Sound machines)(Product/service evaluation)

Sound machines, which can make you feel like you're in a forest or at the beach, worked almost as well as drugs at putting survey respondents to sleep. We put three models at three price points to the test.

A group of panelists who said they had trouble sleeping tried the devices for 10 nights and evaluated whether the machines blocked out most intruding noises and helped them fall asleep faster and stay asleep longer. Each machine was tested by at least 10 panelists.

For the first seven days, the panelists set the machines to white noise or a comparable setting that sounds like a fan or a soft waterfall. Then the group had three additional days to use the machine with any of the other sounds offered, such as a steady rainfall or a flowing stream.

Research shows that white noise can increase sleep quality by reducing the time it takes to fall asleep and the number of times you're awakened while sleeping.

"You don't need to have a bad sleep problem to benefit from white noise in the background," says David N. Neubauer, M.D., associate director of the Johns Hopkins Sleep Disorders Center. "I'm sort of an evangelist about these machines."

Perhaps Neubauer is on to something: In our tests, all three of the units blocked out at least some unwanted sounds, and most of the people left the devices on all night. Plus, all of the machines were small and could easily be plugged in and placed on a nightstand or dresser.

If unwelcome sounds keep you awake, try turning on your air conditioner's fan, a regular fan, or an air cleaner. And check out what our panelists thought of these sound machines: