This does not surprise me, nor does "lack of x will kill you" and the same goes for "too much of x will harm you". Just do things in moderation, or do what you feel you need. Our bodies seem to be pretty smart and often work themselves out - so just listen to it. If you feel tired, go to sleep. If you're hungry, then eat.

For biologists and doctors, it might be fun/interesting to study but for the rest of us I think we should just use common sense and listen to our bodies. I personally abhor these "fads".