Compared to the early 2370s uniform (Voyagers) they looked uncomfortable I don't know how the cast didn't sweat buckets in them especially Avery wearing his Vest under his jacket
It could have been knit nylon like spandex. Spandex isn't very warm, I don't think. I wear that type of stuff under my fencing uniform. It drugs out quickly too if you do sweat.
Even though it's intended that Sisko always wore the vest under his jacket, I don't think Avery Brooks actually wore the vest unless it had to be seen.
IRL, I can’t say about the comfort of the costumes… …But in the 23rd century, the uniforms were thermostatically controlled: KIRK: Suit temperatures to seventy two.
I used to think they looked uncomfortable, but the turtlenecks are a thinner fabric than I initially thought. And depending on the temperature of the ship/station, that jacket may make the wearer quite comfortable.
Vest, shirt, waistcoat, jacket... That’s actually pretty standard wear for blokes for much of 20the century. But the jackets close higher, I suppose. It then nehru collars and priest jackets close higher still.