Sleep-deprived hospital doctors don’t realise how much their performance is impaired after repeated night shifts, Australian research suggests.

Researchers tracked the sleep patterns of 52 ICU staff at Austin Health in Melbourne during day, evening and night shifts and administered reaction-time tests and subjective sleepiness assessments during multiple shifts.

They found that alertness, measured by reaction time during tests, was 15% worse during night shifts compared with day shifts.

Except for their first night shift, doctors and nurses overestimated their alertness in the subjective assessments, in comparison with the objective test results.