Although many studies have detailed the consequences of shift work in nurses concerning health, fatigue, sleepiness, or medical errors, no study has been carried out trying to disentangle the contribution of sleepiness and fatigue associated to shift work from the attentional performance. The aim of this pilot study is (A) to investigate the effects of an 8-h rapidly rotating shift on fatigue and sleepiness among staff nurses and (B) how these factors affect their psychomotor performance. Fourteen nurses were selected for a within-subject cross-sectional study according to this sequence of shifts: morning⁻afternoon⁻night, which were compared as function of tiredness, sleepiness, and performance at the Psychomotor Vigilance Task (PVT). Subsequently, a within-subject Analysis of Covariance (ANCOVA) evaluated if the observed differences between shifts persist when the contribution of sleepiness is controlled. Our results clearly indicate that night shifts are associated with significant greater sleepiness and tiredness, and worsened performance at the PVT. As hypothesized, ANCOVA showed that these differences disappear when the contribution of sleepiness is controlled. Results point to a lower psychomotor performance in night compared to day shifts that depends on sleepiness. Hence, interventions to minimize the consequences of the night shift should consider a reduction of sleepiness.
Keywords: Psychomotor Vigilance Task (PVT); shift work; sleepiness; tiredness; vigilance.