Makes me wonder if the nurses in the control group were around the nurses working fewer hours or if they otherwise knew each other (unclear to me from the artic

Makes me wonder if the nurses in the control group were around the nurses working fewer hours or if they otherwise knew each other (unclear to me from the article). It could just be that the nurses working the extra hours were annoyed that the others were not and so took more days off telling themselves they deserved it since they were working more hours anyway.