Heat, infrared and the body's response
Sudorific effect
Sudorific means causing sweating; diaphoretic is its synonym. Both are genuine English words, but they are dated, and current physiology says sweating, diaphoresis or sudomotor function. "Sudorific effect" in sauna material simply means the session makes you sweat.
Also called diaphoretic, diaphoresis, sweating response, sudomotor
Is the word current? Partly. Sudorific and diaphoretic both appear in standard dictionaries with the same meaning, promoting or causing sweat, and both entered English from Latin and Greek respectively by way of herbal medicine, where a sudorific was a remedy given to induce sweating. In modern clinical and physiological writing sudorific is essentially archaic. Diaphoresis survives as a clinical noun, and the standard technical adjective for the nervous control of sweating is sudomotor. “Sudorific effect” as a compound phrase is sauna and wellness usage rather than scientific terminology, and it means nothing more or less than sweating.
What it describes. Humans have roughly two to four million eccrine sweat glands. When core or skin temperature rises, sympathetic cholinergic nerves drive them to secrete a dilute filtrate onto the skin. Sweat is about 99 per cent water, with sodium and chloride, potassium, lactate, urea and ammonia, and traces of many other substances. Cooling comes from evaporation rather than from the sweat itself — which is why a humid sauna produces heavy sweating and little cooling.
Reading sweat volume. How much someone sweats reflects the heat and humidity of the sauna, how well hydrated they are and how heat-acclimatised they have become.
Why it matters here
Clients tend to judge a session by how much they sweat. Sweat volume mostly reflects the heat and humidity of the sauna, which is a useful thing to be able to explain at the front desk.