stereo next door that has kept us awake. Indeed, experts say the intensity, abruptness, regularity, intrusiveness, familiarity and regularity of noises all affect sleep.
Noises at levels as low as 40 decibels or as high as 70 decibels generally keep us awake. Interestingly, however, the absence of a familiar noise can also disrupt sleep. City dwellers may have trouble falling asleep without the familiar sounds of traffic. Or a traveler may find it difficult to sleep without the familiar tick, tick, tick of the alarm clock at home.
Some noises, although annoying at first, can gradually be ignored, allowing sleep to follow. Studies show people can get used to noises such as city traffic in about one week. However, important noises, like a parent's baby crying, a smoke alarm or even one's own name being called, are not easily assimilated and generally snap us awake.
Experts are also studying the ability of certain sounds to induce sleep. "White noise," such as caused by a fan, air conditioner, or radio static, can often block out unwanted noise and encourage sleep.