The Impact of Shift Work on Sleep, Alertness and Performance in Healthcare Workers

Abstract

Shift work is associated with impaired alertness and performance due to sleep loss and circadian misalignment. This study examined sleep between shift types (day, evening, night), and alertness and performance during day and night shifts in 52 intensive care workers. Sleep and wake duration between shifts were evaluated using wrist actigraphs and diaries. Subjective sleepiness (Karolinska Sleepiness Scale, KSS) and Psychomotor Vigilance Test (PVT) performance were examined during day shift, and on the first and subsequent night shifts (3rd, 4th or 5th). Circadian phase was assessed using urinary 6-sulphatoxymelatonin rhythms. Sleep was most restricted between consecutive night shifts (5.74 ± 1.30 h), consecutive day shifts (5.83 ± 0.92 h) and between evening and day shifts (5.20 ± 0.90 h). KSS and PVT mean reaction times were higher at the end of the first and subsequent night shift compared to day shift, with KSS highest at the end of the first night. On nights, working during the circadian acrophase of the urinary melatonin rhythm led to poorer outcomes on the KSS and PVT. In rotating shift workers, early day shifts can be associated with similar sleep restriction to night shifts, particularly when scheduled immediately following an evening shift. Alertness and performance remain most impaired during night shifts given the lack of circadian adaptation to night work. Although healthcare workers perceive themselves to be less alert on the first night shift compared to subsequent night shifts, objective performance is equally impaired on subsequent nights.

Role of nocturnal light intensity on adaptation to three consecutive night shifts: a counterbalanced crossover study

“…Overall, we did not find that PVT performance improved with consecutive shifts, contrary to some previous studies 19 25. A greater increase in attentional lapses during the first shift than on subsequent shifts has been reported to indicate more pronounced cognitive deficits due to greater sleep pressure on the first shift 11 19. However, in field studies not controlling the duration and timing of sleep after night shifts, the risk of accidents or injuries relative to the first shift has been reported to increase with successive shifts 17.…”

“…Overall, the subjective alertness improved on nights 2 and 3 compared with night 1. Similar findings have also been reported previously for consecutive night shifts, indicating entrainment to night work and/or reduced homeostatic sleep pressure after the first shift, as workers are typically awake longer prior to the first than prior to subsequent night shifts 11–13 24. The reduced sleepiness with bright compared with standard light is in line with previous reports on the alerting effect of bright light 23 26 29.…”

“…The deterioration of performance as assessed with the PVT was evident in both a general slowing of RTs and an increase in number of attentional lapses during night shifts, in line with previous studies 7 8 11. However, participants had fewer attentional lapses and faster RTs in bright than in standard light, similar to previous reports,22 25 28 and these effects were evident already during the first shift.…”

“…The decrement of subjective alertness during night shifts is in line with previous studies finding that KSS score increases from 4–5 at 23:00 to 7–8 late in the shift 10–13. Overall, the subjective alertness improved on nights 2 and 3 compared with night 1.…”

“…About 19% of workers in Europe report working during the night at least once a month 1. In addition to adverse health effects associated with long-term night work,2–6 immediate effects are manifested as deterioration of alertness and neurobehavioural performance during night shifts 7–11. Studies have consistently reported increased sleepiness,9–13 greater number of attentional lapses and slowing of responses during night shifts,8 11 which are associated with an increased risk of accidents and injuries 7 14–17…”