Sleep health and predicted cognitive effectiveness of nurses working 12-hour shifts: an observational study.

Background: Due to the 24hr nature of society, shift work has become an integral part of many industries. Within the literature there exists an abundance of evidence linking shift work-related sleep restriction and fatigue with errors, accidents, and adverse long-term health outcomes.

Objective: The study goal was to physiologically measure sleep patterns and predicted cognitive decline of nurses working both 12hr day and night shifts to address the growing concern about sleep restriction among healthcare workers.

Design: This study presents the results of a quasi-experimental, mixed between-within design where the sleep of 12hr day and night shift nurses was measured using ReadiBand wrist actigraphs. The between groups component was comprised of day v. night shift nurses. The within groups component was comprised of two separate measurement periods for each nurse-once for three consecutive days while they were working shifts (on duty) and once for three consecutive days off work (off duty).

Setting: Participants wore the wrist actigraph at home and in the hospital, and were instructed to adhere to their regular sleep schedule.

Participants: Participants were recruited from two hospitals in Washington State (n=90). Participants were 48 night- and 42 day-shift nurses. All participants worked 12-hour shifts.

Methods: Sleep was measured using ReadiBand wrist actigraphs, which are licensed with the Sleep, Activity, Fatigue, and Task Effectiveness (SAFTE) Alertness Score model, a biomathematical model that predicts cognitive effectiveness based on sleep/wake schedule. ReadiBands also calculate sleep quantity, sleep efficiency, and sleep latency. Results were analysed in SPSS (v26) through multilevel modelling.

Results: Differences were observed in sleep quantity, efficiency, and latency based on shift type (day vs. night) and shift duty (on vs. off). The most extreme differences, however, were noted in cognitive effectiveness (SAFTE), whereby night shift nurses experienced substantial decline-frequently into the "high risk" zone-throughout their shifts compared to day shift nurses.

Conclusions: The present study identifies sleep characteristics that differ between day and night nurses working 12-hour shifts using objective measurements of sleep. Biomathematical modelling can offer a novel method to estimate hours of greatest cognitive decline, and have implications for policy around shift duration, timing, and overtime allocation.