寝ね落おち

noun, noun or participle which takes 'suru'

falling asleep while doing something; dozing off mid-activity

Colloquial term, especially common in online chat or gaming when someone suddenly stops responding because they fell asleep. Also used more broadly for dozing off during any activity.

• 昨さく夜やはゲーム中ちゅうに寝ね落おちしてしまった。

  Last night I dozed off in the middle of a game.

• チャット