"Pyjama" is a Persian word that came into English via Urdu and describes an article of clothing which is also of Persian origin. The first person recorded in English as wearing pyjamas was Tippoo Sultan in 1800. So obviously WAV can't wear them.

"Depends" is of Latin origin so that's out too.

The obvious article of nightwear with a purely Anglo-Saxon name is "straitjacket".