Would be nice to have more of a control with non coffee drinkers.

How even small lifestyle habits, like when you drink your coffee, can have an impact on life

I think it’s worth accompanying this study with the Simpson’s Paradox [0]. I don’t want to dismiss the conclusions of the paper, but temper expectations for individuals considering lifestyle changes.

[0] - https://en.m.wikipedia.org/wiki/Simpson%27s_paradox

kinda obvious: you drink coffee late, have trouble sleeping, and all kind of consequences as result..

I wish they'd used hours after waking/before sleeping vs simply defining morning as between 4am and 12:00pm or evening as being between 5pm and 4:am

People who wake and work later would normally drink coffee more often at later hours and there's already a bunch a research showing 2nd/3rd shifts can cause health issues which wouldn't show up in the people who get up at 5am and have a cup or two in the next few hours.

Nutrition and psychology studies with soundbite conclusions like this almost always fail to replicate.