My own experience suggests that shifts seem easy enough when you're young, but they're just like cigarettes. The effects hit you later when you're older and the damage is already done. There is no doubt whatsoever that shift workers (and despite their controlled hours, pilots too) have reduced average life spans. Of my co-workers who reached retirement, not one has lasted more than five years after they retired and that doesn't consider those who died before they ever drew their pensions. Out of twenty in our section we have five over fifty. Two have had coronary bypass operations and one has intermittent claudication - none are smokers, but all were long-time shift workers. It may be true that people are living longer these days but that doesn't apply to engineering workers who are still stuck with a life expectancy of only 68 years.
There could be a number of other factors in the work conditions responsible for the reduced life spans of shift workers, particularly in the engineering world, but diurnal disturbance is the prime suspect. For example, Hospital Doctors, Nurses and Security Guards don't work with hazardous chemicals and processes yet they are equally affected. If only the unions had spent some time and money on supporting scientific investigation of the long term health effects of shift work instead of negotiating crappy shift pay agreements, we might all have been better off. As it is, I seem to have sold ten years of my life for forty quid a week shift pay back in the seventies.
24/7 working IS needed in many industries but there has to be some way of reducing damage to the health. Shift rotations must give longer rest periods between night duties so that diurnal disturbances are minimised. Perhaps longer holidays for shift workers may be required. All these will no doubt increase costs, but proper scientific investigation IS now finally taking place and I suspect that when the results are out and the lawsuits begin, the bean counters will sit up and take notice.
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Through difficulties to the cinema