Graveyard shifts can bring on the actual grave?

In the ‘I never would have believed it’ category:

Overnight shift to be classified as ‘probable’ cancer cause

LONDON, England (AP) — Like UV rays and diesel exhaust fumes, working the graveyard shift will soon be listed as a “probable” cause of cancer.

It is a surprising step validating a concept once considered wacky. And it is based on research that finds higher rates of breast and prostate cancer among women and men whose work day starts after dark.

Next month, the International Agency for Research on Cancer, the cancer arm of the World Health Organization, will add overnight shift work as a probable carcinogen.

The American Cancer Society says it will likely follow. Up to now, the U.S. organization has considered the work-cancer link to be “uncertain, controversial or unproven.”

The higher cancer rates don’t prove working overnight can cause cancer. There may be other factors common among graveyard shift workers that raise their risk for cancer.

Hmmm. First thoughts: I’ve always wondered why we have to have a 24 hour world.  Also, insurance rates to rise on night shift workers.


  1. Hmm, GruntDoc,

    Who works night shifts, besides you? Aren’t a lot of second and third shift (night shift) jobs often stressy and more often blue collar/lower paying=lacking health care benefits?

    Besides you ER docs, there are a lot of cab drivers, restaurant workers, factory workers, etc. that work nights. Not too much of whitebread middle America and certainly little of the more well-off.

    My brother has been working mostly 2nd and 3rd shifts for 30 years. Virtually impossible for him to quit smoking in an entirely smokers environment. Plus, folks tend to skip going into the clinic for minor health woes if it means missing an opportunity to sleep or means missing employment (w/o sick leave). They just wait until it is really bad.

    Yeah, something about 3rd shift might result in more cancers. I have a feeling it has to do with cigarettes and lack of general health care. What do you think?


  2. Merry,
    I don’t know. We’ll have to see what the research comes up with as associations (there will not be clear causes). I might be smoking, though there are plenty of day-shift smokers, so I don’t know how that will change cancer rates.

    My money’s on cortisol (steriods that are circadian in day-shift lab rats), but that’s just a guess.

  3. I am reallllly slow on the uptake babe. What do you mean “I might be smoking”? You are hot? You smoke? You are just theorizing that people who work nights might or might NOT smoke? (Secretly hoping you are smoking — ya hottie)

  4. crud, didn’t really articulate that very well. Meant: you are thinking some sort of reaction to sunlight/daylight is kindly or suppressing carcinogenic actions? Or that nighttime activity exacerbates them?

    What about people who work nights but also visit tanning booths (there must be a fine, large sample of them??)

  5. I think there is a lot to this, and I agree that cortisol also plays a vital role.

    Melatonin is only triggered by darkness, and it is our primary rest and repair hormone. It controls estrogen levels, which is why it is the hormone cancers resulting from estrogen dominance that are affected by night-time light, as melatonin is suppressed.

    Before the invention of the light bulb we used to spend far more time each 24 hour period in the dark, and now with artificial night-time light, cortisol levels are frequently too high in the evening, commonly contributing to insomnia, poor quality sleep, blood-sugar levels that are too high (cortisol raises blood sugar), insulin levels that are too high, and eventually possibly type 2 diabetes, heart disease, osteoporosis, or cancer. An imbalance in cortisol wreaks havoc with the endocrine system, also impairing thyroid function, frequently resulting in hypothyroid. So, getting enough dark time (9 to 9.5 hours a night – say 10pm to 7am) can go a long way to rebalancing hormonal function in the body. If one can get past the sensational tone, a well researched book on this topic is called “Lights Out, Sleep, Sugar, and Survival” by Wiley and Formby.

    There is actually a lot of research on this topic – good to know the news is finally getting out!

  6. yeah, if they have insurance in the first place… My sister works the nightshift where she works and has none. She claims she can’t afford it, but she can afford every halloween thing that every store has to offer throughout the year? Anyway, yeah, she read about this, and thought that she should get a payraise for the higher risk.

  7. I’d heard recently the same thing about nightshifts and heart disease – supposedly there’s an increased risk in both men and women of cardiovascular disease in people who work a certain number of night shifts for a certain number of years (clearly, my evidence is sketchy!).

  8. TheNewGuy says:

    Can’t say I’m surprised… I worked nothing but nights for years, and I’m convinced that the whole circadian dysrhythmia phenomenon takes years off your life.

  9. I had to laugh at your comment about a 24 hour world. People don’t get sick on a 9-5 schedule as you well know. Nursing has got to be the hardest hit segment of the population for third shift illness. It’s not like we can tell patients to look after themselves after nine pm.
    Just anecdotally in my unit in the last two years: two breast cancers, three premature babies which all died, back, back and more back simple muscle strains all discs that have “blown out” in multiples. It may be fatigue, stress or screwed up clocks, all I know is nurses on the night shift get sick a lot.

  10. Well, as a student by day, scribe by night, I can happily say that between the effect of excessive caffeine consumption, my sedentary study habits, lack of proper diet, and now work habits, I’m screwed.


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