Where does “бессонница” come from?
бессонница (Russian) comes from Russian бессо́нный, from Russian сон, from Proto-Slavic sъ̀nъ, from Proto-Balto-Slavic supnas, from Proto-Indo-European supnós, from Proto-Indo-European swóp-r̥ ~ swép-n̥s, from Proto-Indo-European swep- — to sleep.
бессонница (Russian): insomnia, sleeplessness
Ancestry of “бессонница”, step by step