Five Sleep Strategies (IMAGE) Vanderbilt University Caption The study found that night nurses used five distinct sleep strategies illustrated by this figure. The schedules cover eight days (A to H). The work shift is shown in dark gray; sleep time is shown in red; and free time is shown in light grey. The bar graph in the lower right shows how poorly adapted the nurses were who followed the different schedules. The night stay strategy was not included because it was used by so few nurses. Credit Johnson Laboratory, Vanderbilt University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.