What patients endure, it turns out, borders occasionally on deafening. A study this year from the University of Chicago found that average noise levels in a hospital room easily exceeded the 30 decibels, slightly louder than a whisper, recommended by the World Health Organization, and peak noise levels sometimes approached the level of a chain saw. Not surprisingly, patients in the loudest rooms suffered most, losing as much as an hour or more of sleep a night compared with those in the quietest rooms. And for every hour of sleep lost, the patients' blood pressure increased by as much as six points.