Target A Blood Level, Not A Dose
The central mistake Gmanac watched play out across hundreds of patients and in every major vitamin D study is treating D like a drug with a fixed dose. Hormones do not work that way. Estrogen, thyroid, testosterone, all of them are managed by blood level, not by a universal milligram count, because too much and too little both produce the same result: the body stops functioning normally. Vitamin D is a hormone that was mislabeled a vitamin in the 1940s, and that labeling error has led doctors and supplement companies to hand out flat dose recommendations as if the hormone behaves differently from every other hormone in the body. Gmanac found through her patient population that the number that moved the needle on sleep was a blood level above 60 nanograms per milliliter. Patients on CPAP whose sleep had not improved for a year reported better sleep and resolution of headaches within a month of bringing their levels into that range. The dose required to reach it varied enormously. Most of her patients needed around 10,000 IUs daily. One patient, Meline, needed 30,000 IUs daily for four years and her level stayed in the 60s the entire time, meaning her body was consuming that amount rather than accumulating it. The dose is irrelevant without the level. The level is what the brain responds to.