Typical Sleep Patterns Are Absent in Mechanically Ventilated Patients and Their Circadian Melatonin Rhythm is Evident But the Timing is Altered by the ICU Environment

The authors performed a prospective observational study of 25 mechanically ventilated and sedated patients admitted to a North American ICU. The study investigators evaluated whether circadian and homeostatic processes were functioning normally and appropriately in these patients in order to maintain normal sleep–wake patterns. The authors discovered that these patients appear to have a “free running circadian pacemaker”. The investigators found that EEG activity demonstrated slow wave sleep that was similarly distributed during the 24 hour period of evaluation, indicating absence of changes between wake and sleep states. This study highlights the importance of providing an ICU environment that promotes a normal circadian rhythm.