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Light exposure at night predicts incidence of cardiovascular diseases

medrxiv.org

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Re: Light exposure at night predicts incidence of cardiovascular diseases

#101

Post by trollbridge »

lo0dot0 wrote: post #91
ethan_smith wrote: post #84

Earlier quoted context omitted.

The study measured personal light exposure via wrist-worn trackers for a week rather than using geographic light pollution data, which would better control for the urban air quality confounding you've identified.

No, measuring light doesn't remove the air quality confounder. Measuring air quality would allow to remove the air quality confounder. What are you smoking?

It turns out they took both rural and urban samples too and there was no meaningful difference between the two populations. Exposure to indoor overhead light is probably far more significant than what streams in your window with the drapes shut.

Re: Light exposure at night predicts incidence of cardiovascular diseases

#102

Post by trollbridge »

giraffe_lady wrote: post #26
codingrightnow wrote: post #13

Earlier quoted context omitted.

Maybe they're exposed to light at night because they're awake at night more often, possibly shift workers, which we already know is unhealthy. I doubt just having light on is causing the effect.

Yes they tracked hours of light exposure (above some threshold? I don't see that they say.) and found this result in the 90-100th percentile. So almost certainly night shift workers.

They grouped the population into percentiles with 0-50% having quite low exposure (0.62 lux median, range of 0-1.21) vs the 90%-100% percentile being 105 lux (range of 48.3-6400). You can compare the daylight light exposure to the nighttime and basically see what a shift worker would be.

But they already deconfounded for shift workers, so that's irrelevant. And they also showed the amount of light exposure for both night and day.

Re: Light exposure at night predicts incidence of cardiovascular diseases

#103

Post by trollbridge »

ltbarcly3 wrote: post #63
ziofill wrote: post #47

How do they know the causal link? Can it be that people who stay up late sleep less and this causes issues, and there being light is only a consequence of staying up late?

It does not claim a causal link, just correlation.

"Correlation is not causation!" is one of the sillier things that people say when a study comes out with meaningful, interesting data. If nobody ever finds correlations in the first place, then it won't be possible to figure out causation - and we certainly do want to eventually find more causation for things like heart attacks, don't we?

Re: Light exposure at night predicts incidence of cardiovascular diseases

#104

Post by trollbridge »

ekianjo wrote: post #23
patrickhogan1 wrote: post #2

Each participant wore a wrist light tracker for 1 week.

that seems very short

N>88,000, so it has a huge sample size. Most people have the same patterns of sleep and nighttime/daytime habits week to week.

Re: Light exposure at night predicts incidence of cardiovascular diseases

#105

Post by trollbridge »

giraffe_lady wrote: post #28
etimberg wrote: post #14

Is this detecting people who work overnights?

I believe so yes. They tracked hours of light exposure at night over a week, and found this result in the 90-100th percentile. The 90th percentile here is pretty much going to be people working at night yeah.

The percentiles of 50-60, 60-70, 70-80, and 80-90, however, are obviously not shift workers (unless they're shift workers working in the dark); you compare the lowest percentile of daylight light exposure to the highest percentile of nighttime light exposure, and see that there just aren't that many shift workers present in the study. About 13% of the UK population is considered to be nighttime workers. We can safely assume nighttime workers aren't represented in the 50%-90% percentile, because there simply aren't enough of them to go around, and would not be statistically significant.

Re: Light exposure at night predicts incidence of cardiovascular diseases

#108

Post by trollbridge »

3eb7988a1663 wrote: post #49
trollbridge wrote: post #21

Earlier quoted context omitted.

Good catch, although there are plenty of studies and even metastudies on that topic (eg https://pmc.ncbi.nlm.nih.gov/articles/PMC11129786/ ); generally speaking, the healthiest people are those who work "normal" day shifts with "normal" hours (full time; not part time; no overtime).

Isn't that just a rough proxy for wealth? Outside of the coke-fueled hedge fund manager, the poor are more likely to have over-time/shift-work/irregular work hours. Your standard office drone can have a consistent work/sleep schedule.

It's not, because the study specifically disambiguated for socioeconomic status.

The effect was also seen outside of the night worker population (13% of the population).

Re: Light exposure at night predicts incidence of cardiovascular diseases

#110

Post by trollbridge »

bregma wrote: post #86
trollbridge wrote: post #20

Earlier quoted context omitted.

I've always wondered about people who say that... there's enough light (particularly when it's not a new moon) to see to go the bathroom, but maybe my eyes adjust to the light better?

You must live in the city.

I live in a rural area.
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