Increases in sex hormone binding globulin due to caffeine are generally not a significant concern at typical safe dosages (1-3 mg/kg body weight).

“However, when one controls as well as one can for all the various factors that could impact hormones, what one discovers is that caffeine intake, at least at the dosages we talked about earlier, 1 two 3 milligrams per kilogram of body weight or even up to double that, that there are no consistent increases or reductions in testosterone or estrogen in men or women that can be directly attributed to the caffeine intake.”

“So again, the increases in sex hormone binding globulin were not so significant that, at least to my mind, they seem like a concern, although I think that it is worth noting that if you're going to consume caffeine that you probably want to consume caffeine in a way that is in dosages and with the sort of timing that will allow you to get away with ingesting caffeine but not to excess, so to derive the benefits of caffeine without for instance driving up sex hormone binding globulin too far.”

“With all that said, there does appear to be a relationship between caffeine intake and so-called sex hormone binding globulin, which is a protein present in the body of both men and women that binds to the sex steroid hormones-- testosterone and estrogen-- and prevents them from being in their free or active form.”

“Only if it affects your sleep. So, it works on adenazine and it can actually slightly improve allergies as well, but uh negligible effect otherwise.”