Sedation is very important in critical care. Critically ill patients are submitted to many stressor factors that have potential to affect longterm outcomes. However, oversedation is associated with increased morbidity, including increased time of mechanical ventilation and ICU stay and longterm psychological complications. Daily interruption of sedation is associated with less time under mechanical ventilation and less posttraumatic stress disorder. Intermittent sedation, when compared with continuous sedation, is also associated with decreased time of mechanical ventilation. The aim of this study is to compare intermittent sedation with daily interruption. Our primary endpoint is free-days of mechanical ventilation in 28 days.