Shift length and productivity: 12-h and 8-h

I’ve covered a bit on the links between shift lengths and safety/risk. (Cliffs notes: it’s more complicated than just shift hours and involves a raft of factors), but don’t think I’ve covered much on the links between shift length and productivity.

Ferguson and Dawson’s excellent 2011 paper covered a range of topics on the relative advantages and limitations of 12-h vs 8-h shifts (i.e. sleep quality, health indices, morale and satisfaction, alertness, performance and more) – including studies on productivity and absenteeism.

As per the attached table, they note that while “It is reasonable to hypothesize that 12-h shifts would not be so widespread if they were associated with reduced productivity”, recent research “appears not to support that position”.

They discuss a medical study looking at the productivity of residents. On 9-h shifts, 1.15 patients were seen every hour compared to 1.06 patients per hour on 12-h shifts.

Thus, “Total patient encounters in the emergency department fell following the introduction of 12-h shifts. Such studies show quite clearly that on a measure of productivity alone,12s are not ‘better’ (p5).

Interestingly, they explain that “People are also likely to pace themselves across a 12-h shift such that their hourly output is less but they maintain a constant level for more hours” (p5).

They also cover some work around absenteeism. One mining study looked at the change from 8-h to 12-h, where higher absenteeism was observed in a group of employees in the mine who “worked unregulated and frequent overtime” (p5).

It didn’t cover shift/fatigue and presenteeism though, so I’ll cover that another time.

There’s lots of conflicting and contradictory evidence in the overall discussion between benefits and limits of 12-h, so lots more can be said here. However, the authors aptly address the question in the title of their paper: “12-h or 8-h shifts? It depends”.