If I remember correctly....no matter what a girl wears there were comments so at least I was comfortable in PJ/sweatpants. It was also less laundry to do. One outfit for the whole day
My general attitude was F it. Im here to learn and sleep when I was not actively learning anything. A lot easier to take naps in PJs. My circadian rhythm has always been slightly later so being at school at 720am was torture. I would fall asleep in the shower sometimes. I could not fall asleep before 1130. I tried. I took melatonin. I smoked weed. I would just lay there in bed. Id get off. Id have warm milk. I played sports. I had a PT job. Multiple AP classes. I was busy and tired but it Did. Not. Matter.
Plus do you remember how HOT schools are in the winter. PJs are the perfect level of coverage and breathability. T-shirt and hoodie on top. T-shirt for normal classroom and hoodie for random cool classroom (one with lots of windows) and for going in/out of the school.