ABSTRACT: The primary mission of any intensive care unit (ICU) is to provide critically ill patients with high-quality care and an atmosphere in which to recuperate. However, all too often, the intensive environment, which is often busy, chaotic, and noisy, may contribute to just the opposite. Patients overstimulated with noise, lights, and other distractions often suffer from sleep deprivation. Research in medicine and nursing has shown that sleep deprivation can have detrimental effects on an ailing patient. Therefore, a quiet time program was developed in the neuro-ICU to reduce noise and light levels, with the ultimate goal to allow sleep. Quiet time, a period of reduced controllable noise and light, took place twice daily coinciding with circadian rhythms. The study included 50 neuro-ICU patients, 35 observed during day hours and 15 observed during night hours. Noise and light levels were measured at multiple locations before, during, and after quiet time hours. Patients' sleep behavior was recorded every half hour, beginning 1/2 hour before quiet time until 30 minutes after. Analysis of data, adjusted for multiple testing and repeated measures on patients, demonstrated significantly lower noise and light levels during day shift quiet time. In addition, patients were significantly more likely to be observed sleeping during day shift quiet time hours.