How the chance of missing the alarm during an on-call shift affects pre-bed anxiety, sleep and next day cognitive performance

This study investigated how the chance of missing an alarm affects pre-bed anxiety, sleep and next day cognitive performance during on-call shifts. Participants (n = 24) completed one adaptation night, one control night and two on-call nights in a time-isolated sleep laboratory. On one of the on-call nights, participants were informed that they would be woken by a loud alarm that they would definitely not be able to sleep through (low chance of missing the alarm). On the other on-call night, participants were informed that they would be woken by a quiet alarm that they may sleep through (high chance of missing the alarm). The two on-call nights were counterbalanced. Pre-bed anxiety was measured using the State Trait Anxiety Inventory x-1, while sleep macro- and micro-architecture was examined via routine polysomnography and power spectral analyses respectively. Following each sleep, cognitive performance was assessed four times (0930, 1200, 1430, 1700) using the 10-min psychomotor vigilance task (PVT). Results indicated that while pre-bed anxiety was similarly increased during both high and low chance of missing the on-call alarm conditions compared with control, only in the high chance condition was total sleep time shorter and sleep efficiency lower compared with the control condition. However, more wake after sleep onset was found in the low chance condition compared with control. PVT data indicate that response times (mean reciprocal and mean fastest 10% of reaction time) were fastest in the low chance condition, indicating better performance when compared with both other conditions. However, there were significantly more lapses in the low chance condition compared with control. No significant EEG power spectral differences were observed. As such, it appears that there are detrimental effects of both on-call conditions on anxiety, sleep and performance, with sleep poorest when the chance of missing the alarm is high. The adverse impacts on sleep and performance outcomes while on-call may be mitigated by the implementation of workplace systems to reduce the chance of missing alarms (e.g., having two available options for contacting on-call workers).