if had been then I would not have called it to be superficial. I mistakenly assumed with the tone of the article, that it would make as strong of a point that it could, and this article, presented very little information about all these additional constraints and steps you mentioned.
Now knowing about all these additional steps, I'm still left pondering - what if high energy people shifted their sleep patterns? I'm a night owl, and I'm generally a high energy kind of person, but if I was to shift my sleep so that I went to bed earlier and woke up earlier (although tough to pull off for me), maybe my energy would go with me, shifting to earlier in the day.
I think that would make a good follow up study: take those night owls and perhaps the early rises as well, and shift their sleep up and then do all these measurements again to see how it affected them. Did they drop in energy, or did their energy go with them through the transition (giving them time to adjust as well).