Table 1 Calculation of total risk scores.

Risk factor	Lower risk (0 points)	Significant risk (1 point)	Higher risk (2 points)
Hours worked	<50	50–70	>70
Shift length (hours)	All shifts <10	1 Shift ⩾14	At least 2 shifts ⩾14
Extended shifts	No shift longer than scheduled, all shifts <24 hours	At least 1 shift longer than scheduled but <24 hours	At least 1 shift ⩾24 hours
On call (days)	0–2	3–6	7
Night duty (n)	0–1	2	⩾3
Breaks <10 hours	0	1–2	>2
24‐Hour breaks	⩾2	1	0
Schedule change	No change, predictable schedule	Change, predictable schedule	Change, unpredictable schedule
Sleep at night (23:00–07:00), No of nights	6–7	4–5	0–3
Enough sleep, No of days	6–7	4–5	0–3