Welcome to the fourth and final installment of this mini-series on cortisol. You may know cortisol as "the stress hormone", but if you have been following along, by now you realize it does a lot more. You may be wondering: if cortisol helps regulate... pretty much everything... why does it have this bad reputation?
And if you are just jumping in, here are parts I-III:
So is it a lie that cortisol is bad?
Some of the cortisol-stigma comes from the time before we knew about the rhythm of cortisol. To early researchers, time of day (which causes >70% of the variance1) was "nuisance variation." A nuisance to measure, but not a nuisance to the body! Strong daily variation is what we want to see.
You may be wondering: if cortisol helps regulate... pretty much everything... why does it have this poor reputation?
As it turns out, a flattened cortisol slope (lack of variance) is the problem when it comes to cortisol. Think about what would would happen if:
cortisol levels didn't rise in the morning (…
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