Because of the nature of shift work, there is no perfect schedule that incorporates shifts. The best schedule is one that has lots of employee input. When employees have input, it helps them to accept the schedule they are working and leads to less complaining. However there are strategies that may be used when creating schedules.
Length of Rotation
The choice here is whether to have a short or long rotation.
A long rotation would consist of working a stretch of night shifts for 4 to 6 weeks. With this amount of time the person would probably only need to work nights once a year. With a period this long a persons circadian rhythm will change to the night shift time period. Although to make this work the person must keep their sleep/wake times the same even on their days off. This is a problem for many people as they would tend to try to return to a day shift type time period on their days off and their circadian rhythm would remain disoriented. It must be remembered that it takes at least 1 week for the circadian rhythm to be fully adapted to a new time.
A short rotation would involve no more than 3 night shifts in a row. In this manner the changeover being quick keeps the circadian rhythm from fully resetting. One rotation of shift workers was a 1/1/1 rotation. One afternoon, one day shift and one night shift followed by 2 days off. At this particular plant it works very favourably to the employees.
From my experience I find the shorter the rotation the better. I find when I have worked 1 or 2 night shifts I seem to adjust back to day shift fairly quickly. I have found a longer rotation of 4 to 7 nights to make it very hard to reset my body clock. I find I am unable to return to a normal sleep time until after 2 to 3 days and feel exhausted during that period.
Direction of Rotation
It has been proven a clockwise direction is the easiest on the circadian rhythm. The circadian rhythm is 24 hours in length, so if you go from a days, afternoons to nights rotation you are at least advancing in this direction. This is also known as a phase delay rotation. If you go in a phase advanced rotation, ex. nights, afternoons to days, you are going against this circadian rhythm. Most people will experience less "jet lag" going from east to west than from west to east. It works on the same principle.
As for 12 hour shifts the time change from days to nights is dramatic as they are complete opposites. It may however be beneficial to stay in a phase delay rotation that would be days to nights followed by time off.
Length and Start Time of ShiftsCircadian principles are much easier applied to 8 hour shifts and the clockwise rotation discussed above works well with this but many employees favour 12 hour shifts as they receive one third more days off.
Age can be one of the important factors as to length, as the older we are the less able we are to adjust to the frequent changes that shift work brings about. Ideally an 8 hour day shift suits an older worker better. Younger workers circadian rhythm adapts to change better and shift work sometimes help for arrangement of child care responsibilities.
Another strategy is to have the finishing time of a shift at a period so that the shift worker can still get some sleep during normal sleep time. For example a shift of 10am to 6pm, 6pm to 2 am and 2 am to 10 am. Also staggering of length of shift has been done. For example the day shift is 10 hours, afternoon shift 8 hours and the night shift only 6 hours long.
Depending on the situation any of these may be very favourable to a group of shift workers.
I currently work a rotating 12 hour schedule that encompasses a 35 day cycle of alternating of 2 and 3 day stretches of nights and days for 25 days and a 10 day stretch off after that. I find working 2 night shifts not bad, but the constant rotation each week for 3 weeks from days to nights does seem to take its toll.
What ever shift schedule you end up utilizing, I cannot stress enough the importance of employee input. There is nothing as frustrating as having a manager make up a schedule without employee input. Especially one that is not working shifts or has never worked them for a fair length of time themselves. With employee input using some of the above shift schedule techniques an adequate schedule can be done that serves the need of the employer as well as that of the employee.