Medieval Islamic physicians made a distinction that modern wellness culture has almost entirely lost: between the *mizaj* — the individual constitutional temperament — and the universal prescription. Ibn Sina's canonical medical system held that no two bodies required identical regimens, not because of some vague notion of 'bio-individuality,' but because health was understood as a dynamic equilibrium specific to a person's particular constitution. The practical implication was radical: the right diet, sleep rhythm, or exercise load for one person could be genuinely harmful for another — not metaphorically, but physiologically. What makes this relevant now is that we live in the age of the universal protocol. Intermittent fasting windows, optimal sleep times, step counts — all of it flattened into population-level guidelines that treat your body as an instance of an average. Ibn Sina's framework, synthesized with modern thinking on allostasis — the body's process of achieving stability through constant change rather than fixed set-points — suggests that the goal isn't finding the right routine and holding it. It's developing enough sensitivity to your own baseline that you can read when a regime is working *for this version of you, right now*, rather than against it. The protocol isn't the destination. Your responsiveness to the protocol is.

What is one health practice you follow with confidence — and when did you last actually check whether your body is responding to it the way you assumed it would?

Drawing from Islamic Galenic Medicine (Ibn Sina / Avicenna) synthesized with Allostasis theory (Sterling & Eyer) — Ibn Sina (Avicenna, al-Qanun fi al-Tibb / The Canon of Medicine, c. 1025 CE), synthesized with Peter Sterling and Joseph Eyer's allostasis framework (1988)