更ふかす

godan verb (-su), transitive verb

stay up late; sit up late

Used for intentionally staying awake late into the night, often with 夜を更かす.

• 昨夜ゆうべは遅おそくまで夜よを更ふかしてしまった。

  Last night I ended up staying up late.

• 試し験けん前まえはよく夜よを更ふかして勉べん強きょうする。

  Before exams I often stay up late studying.