The effect on sleep of being on-call: an experimental field study.

The aim of this study was to: (i) gain more insight into the relationship between being on-call and sleep and (ii) investigate the role of stress in this relationship. Data were collected by means of an experimental field study with a within-subject design (two conditions, random order). Ninety-six students participated during two consecutive nights: a reference night and a simulated on-call night without an actual call. Participants were told they could be called at any time during the on-call night. In the case of a call, participants had to perform online tasks for approximately 30 min. Self-reported sleep quality and the extent to which participants experienced stress during the on-call period were assessed by means of short questionnaires. Actigraphy was used to obtain objective sleep measures. Results for actigraphy data revealed no significant within-person differences between conditions. However, participants reported longer sleep onset latencies, more awakenings and more wake after sleep onset during the on-call night than during the reference night. They also reported more sleep problems and a lower overall sleep quality, and felt less recuperated after the on-call night. Perceived stress moderated the relationship between being on-call, on one hand, and the number of awakenings, wake after sleep onset, sleep problems and overall sleep quality, on the other hand. Results show that, even in the absence of an actual call, sleep during on-call nights is of lower quality and has less restorative value - especially when being on-call is experienced as stressful.