Expectation of a loud alarm is not associated with changes in on-call sleep in the laboratory

Anecdotally, people report disturbed sleep when ‘on-call’ and field data suggest that being on-call, even if ‘undisturbed’, may result in sleep disturbance. We investigated changes to sleep when expecting a loud, oncall alarm as compared to sleep when not expecting an alarm. Healthy males (n = 16) aged 24.6 ± 4.0 years took part in a simulated on-call scenario involving two conditions; Control and on-call. Prior to the Control sleep, participants were told that they would not be woken during the night, prior to the on-call sleep, participants were told to expect a loud alarm during the night, following which they were to complete 2 h of testing. Sleep was measured using a standard 5-channel polysomnograhic (PSG) montage. Sleep diaries were used to compare subjective variables; pre- and post-sleep sleepiness and sleep quality. There was no significant difference between the two nights for any of the PSG variables, except for REM where there was a nonsignificant trend (p = .051) with 8 min more REM on the on-call night. Participants were significantly sleepier following the on-call night, likely due to the earlier wake time (p.01). These results question whether simply being oncall is disruptive to sleep or whether disruption is connected to other factors such as likelihood of being called, worry about missing the call and/or the events that follow.