I couldn't find the words "fitness" or "exercise" anywhere in the article. In my opinion any discussion of sleep habits should include exercise (if I was a doctor that's the first thing I'd ask my patients about). The writer does mention coffee and caffeine, which is another good indicator of potential sleep issues.

I used to work vampire hours years ago while an independent. It was fun in some ways, but waking up at lunchtime made me feel like I missed most of the day. Now I'm up before the sunrise and accomplish more (it's also somewhat necessary in my commuting environment).

Find what works for you, but mind your health (says grandma)!