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. Sleep Surface Little research is available and not surprisingly on how much sleeping surfaces affect our slumber. For the most part, we know people sleep better when horizontal and not cramped by space. As with noise, however, women and more mature people appear more sensitive to variations in sleep surfaces.