American here. I read that "formal" pajamas are more common in the UK, and I do read a lot of things set in the UK and France where characters own Real Designated Pajamas. Like, matching top and bottom, with a collar and buttons and piping on the seams and etc. To be honest, I have been interpreting these characters as absolute dorks.
I, and pretty much everyone I know, mostly just wear a soft old t-shirt to sleep, and sweatpants, plaid flannel trousers, or old running / basketball shorts. Imo, if someone in the US has capital p Pajamas, they are probably elderly, 5 years old, or temporarily wearing coordinated ones for a Christmas photo or a commercial.
Where do you and your country fall on the spectrum of pajama formality? Am I correct that Europeans with formal pajamas are still dorks? Or is this more American barbarianism?