Also, Dan Pink has a new book out about timing with some discussion of the 'stages' of our day. Some people have naturally different stages.
https://www.youtube.com/watch?v=qR-NqSpS_cE
https://www.scientificamerican.com/article/timing-is-everyth...
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I'll also second the OP as I'm not what I consider a morning person (when unemployed, more 10a-2a for natural rhythm) but my current job has me getting up around 5:30a. I might be a convert though because, as they said, getting a lot done early is pretty amazing. I like being home by 4 and having a large block of time to do spend however I want. And it translates to weekends too where I find myself up in the world early. I live in LA though so our daylight shifts aren't as drastic in winter as other places.