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Seriously? Couldn't be the case the outdoor night lights only shine the road towards the candy shop?

I don't think they try to draw causal nexus in this study (which is fine, it's not in the scope of a study like this to explain everything).

There are many potentially sound hypotheses one could make e.g. people who live near lots of artificial lights also likely live in urban centers and might work longer and thus have less time to exercise or eat healthy.

Also could be poorer, etc.

Yes, this study doesn’t say that the light is the cause but that “where there’s is more artificial light there’s more diabetes”, not that the light is the cause of the diabetes. There could be lots of connected causes as you said.

Humans evolved linking blue light to daytime.

Blue light is a portion of the visible light spectrum that can have unique effects on alertness, hormone production, and sleep cycles. There are several studies now pointing at evening blue artificial light as the culprit for multiple alignments.

Urban areas, higher sugars consumption

Cancer cells tend not to respond to normal circadian rhythms. Makes sense

Quasi-experimental effect?

More outdoor lighting in city centers -- denser population effect? We know there's an effect of anxiety, diet, etc with those uncontrolled population density variables. I don't see any controls briefly glancing.

So what I'm hearing is having to work night shift gives you diabetes.

Makes sense. There was a study started at UW several years ago that was ended after only one week because the test subjects, young healthy college students, started to develop diabetes. The study? Deprivation of delta sleep. High quality sleep is vital to metabolism. If artificial light deprives you of delta sleep, you’re gonna have problems.

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Fascinating - do you remember the name of the study? Alternatively, do you have links? I'd love to read more on the study

I haven’t read it, but is it plausible form the data and controls that outdoor lights = denser city -> city lifestyle (nightlife, processed foods, stress/noise, etc) -> diabetes

If so, it seems less likely to me that this is some actual light impact and far more likely to be just a marker of lifestyle.

Edit: it said one of the controls was adjusting for “urban/rural area“. I have no idea what that means, but that is at least part of above. I’m unsure how a binary urban/rural is measurable. In any rural environment one that is more lit is going to be more densely populated. I think the same is probably true for urban areas.

Seems like maybe a control for population density might be more useful.

Problem is, the study was ended super early, so I don’t think they published. I think I heard about it during an interview with the lead physician in some documentary. I went looking for it a couple years ago and didn’t find it, however…

If you Google “delta sleep deprivation diabetes” tons of info will come up. Key metabolic functions are known to occur while we sleep.

I’ve known more than a dozen type II diabetics in my life, only one of them was overweight. Several of them had stories of times in their lives when they were sleep deprived (military pilot training, medical school, etc.). We know there’s correlation between weight and diabetes, but it’s not the cause. I’ve known many overweight people who haven’t developed diabetes. I’d bet that a combination of extra weight (which will increase insulin resistance) and sleep apnea (which will reduce deep sleep) is a reliable formula for diabetes.

I really want to stress this: Diabetes has many causes, we tend to oversimplify and blame the victims. It’s a metabolic imbalance and there are several ways to throw it out of balance.

I don’t understand why blue light blocking amber contacts aren’t a thing yet. Obviously they are only useful for after sunset, but that’s a long portion of the day. I would be willing to swap day contacts out for night contacts for the widespread benefits of keeping the photocycle intact.