This is the first study I know that directly tested this - the effects of rotating shifts on longevity - in humans, though some studies of night-shift nurses have shown large increases in breast cancers, stomach ulcers and heart diseases, and similar studies have been done in various rodents and fruitflies:
A study of 3,912-day workers and 4,623 shift workers of the Southeastern Central Railway in Nagpur showed the former lived 3.94 years longer than their counterparts on shift duties, said the study by Atanu Kumar Pati of The School of Life Sciences in Pt Ravishankar Shukla University, Raipur.
Shift work affects the circadian rhythm, the 24-hour cycle in the physiological processes of humans that leads to several sleep-related and social problems.
Circadian rhythms are important in determining the sleeping and feeding patterns of all animals, including humans. Brain wave activity, hormone production, cell regeneration and other biological activities are linked to this daily cycle.
Pati and his colleague K Venu Achari analysed a database of dates of death, retirement and death of each worker and published their findings in the latest issue of "current science".
They also studied data on deaths due to all causes of 594 railway employees, including 282 day workers and 312 shift workers, over a span of 25 years. The cause of death was not documented in the database. An analysis of the data showed that day workers tend to live 3.94 years longer than counterparts working in shifts.
All day workers performed duty between 9 am and 6 pm with an hour-long lunch break from 1 pm and included those on office job and doing miscellaneous duties, the study said.
Those coming for shift duties worked in a rotating system consisting of a day shift (8 am to 4 pm), first night (4 pm to midnight) and second night (midnight to 8 am).
They worked in each shift continuously for six days and had a single day break before resumption of the next shift. The shift workers included running staff, gangmen and those doing miscellaneous jobs.
"The longevity of each worker was computed from the dates of birth, retirement and death," Pati said. The researchers cited a number of animal studies that documented the life-shortening effects of weekly shifting of light-dark cycles.
It has been argued that these effects could be mediated through disruption of the circadian rhythm. Lighting schedule manipulation has also been reported to produce detrimental effects on the lifespan of insects.
Thanks for posting this... my wife has been working as a nurse in a rotating shift hospital for a few years now, its awful! I tracked down the original paper and gave it to her to give to her administrator. Too bad she's on night shifts now so I've got to wait a few more hours before showing it to her.
It is not at all surprising (to me) that rotating shifts shorten life. Not at all.
But, aside from the well-known cancer research, I wonder if anyone's done a similar study of people who've worked the "wrong" shift for many years, same shift all the time. Wonder, too, why some people seem to manage this without great problems while others hate it and burn out. I'm a DSPS patient who's worked days for decades, (trying to) get up in the middle of my natural night, suffering "jet lag" every day. Now that my sleep-wake is more or less under control with melatonin evenings and light box mornings, I'm convinced that all my other daily rhythms are not in sync. My health has deteriorated rapidly since diagnosis (and treatment) 3 years ago. But I can get up at 7, so my specialist is happy.
I note that that rotation is forward, which is the easier of the two, since making the transition from one shift to the next needs only staying up 8 hours.
In a reverse rotation -- days, mornings, nights -- the need is to go to sleep 8 hours early. That's the rub. Nobody can do it.
I left shift rotation in 1988 and my sleep is still badly disturbed.
In general, I try to get people to stop working rotating shifts. For mood disorders in particular, it is one of the most dtrimental lifestyle factors.
"Rotating shifts are associated with shortened lives"
I live in an industrial city (Bhilai) in India. One of the biggest steel plants of India is located in this city. I know many people who work shift and suffer from number of problems. Contribution of Pati and Achari is worthwhile in that shift work shortens life.
I have worked 12 hour straight days, 8 hour rotating shifts, 12 hour rotating shifts. The problem with 12 hour shifts , besides not seeing family, is having time off to do usual business. Those on night shift don't get the night time sleep. I always had a problem sleeping when it was daytime, no matter what I did, blacking out windows, taking melatonin, etc. I proposed that we split the shifts from 1500-0300, for nights; 0300-1500 for days. this would give each time off for usual business, some time for night time sleep. Has anyone ever tried this?