How to reduce circadian misalignment in rotating shift workers

Figures & data

Table 1 Current shift work schedule

Crew or week	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
1	D	D	D	D	X	X	X
2	X	X	X	X	N	N	N
3	N	X	X	X	D	D	D
4	X	N	N	N	X	X	X

Notes: D, day shift; N, night shift; X, days off.

Table 2 Proposed shift work schedule

Crew or week	Monday	Tuesday	Wednesday	Thursday	Friday	Saturday	Sunday
1	D	X	D	D	X	X	X
2	X	N	X	X	N	N	N
3	N	X	N	N	X	X	X
4	X	D	X	X	D	D	D

Notes: The schedules are designed for four crews working 12-hour shifts. For each day, one crew works nights, one crew works days, and two crews are off. All workers rotate through the 4 weeks and then repeat the 4-week sequence. Each week has the usual billing cycle of Monday through Sunday. Thus, each week has three or four 12-hour work shifts, which fulfills the payroll (overtime) constraints of many companies. D, day shift; N, night shift; X, days off.

Figure 1 Light and sleep (dark) schedule for a shift work schedule that rotates between 12-hour day shifts and 12-hour night shifts.

Notes: This schedule is designed to minimize circadian misalignment, improve sleep, improve work performance, and reduce the long-term health risks of shift work. Horizontal lines with dots on both ends – sleep in the dark, short horizontal lines with dots on both ends – naps, sleep (dark) lines with arrow tails and heads pointing to the right – going to bed and waking up a little later is helpful, sleep lines with arrow heads pointing to the left – going to bed earlier is helpful, triangles – the body temperature minimum, a marker for the phase of the circadian clock and the sleepiest time of day. S, sunlight (outdoors); L, bright light from light boxes; M, melatonin (small dose 0.5 mg or 1.0 mg).