Seriously, though - those studies are horrible, mostly because human research has shit controls.

Like, no shit that going to bed early and rising early makes you healthier and more productive in a society where type A personalities rule the world and operate on a 9-5. You either get the dregs of work, or you drag yourself out against your natural schedule to fit theirs. You're constantly tired and that has well demonstrated effects on health. Support systems also work on 9-5, so you're still screwed.

For anything they say to be valid, they'd need a control society run by 4p-12a work hours, so you could go to bed at 2-4a and get a full 8 hours and a relaxed morning ramp up like all those type As do today; then they'd have to demonstrate that the type As still did better in this control society.

FFS, to do financially well you need to be an early riser on East Coast time! To line up with the stock market! If the stock market ran 3-12 PST, how do you think those New York early birds would do with a 230am bad news dump? They'd be hours behind the Pacific night owls who could execute trades when they're coherent and focused and would make more money on those trades.

All they currently show is "lining up with the ruling sleep schedule is easier on your life".