Sleep is critical to the healing process, yet sound sleep in a hospital is notoriously difficult to come by. To get to the source of the problem, a team of nurses conducted a study at the Mayo Clinic in Rochester, Minn. The nurses placed noise dosimeters in patient rooms, and two volunteered to sleep over and note bothersome sounds in a thoracic-surgery unit packed with humming equipment and monitors. Peak dosimeter readings as high as 113 decibels--roughly equivalent to the din of a chain saw or jackhammer--came during the 7 a.m. staff changeover, and the 11 p.m. changeover was also quite noisy. By adopting remedial measures--some as simple as closing doors to patients' rooms and replacing clanking paper-towel dispensers--the staff reduced noise levels more than 80%, according to the report published in the American Journal of Nursing. For convalescing patients, that's better than a lullaby. --D.B.