keep someone up late

keep someone up late (third-person singular simple present keeps someone up late, present participle keeping someone up late, simple past and past participle kept someone up late)

1. To prevent a person from going to bed at their usual time.
   • 2025 October 1, Christian Wolmar, “Rail Minister at the heart of rail reform”, in RAIL, number 1045, page 35:

     Few political careers start when people are in their 70s, but Hendy is actually relishing it, although he is incensed sometimes by the pointlessness of the posturing by the opposition, which keeps him up late. "The bit I don't like is getting home at 0100 or 0200 in the morning because the opposition have been fruitlessly arguing for a long time."

• keep someone up at night

• “keep up”, in Cambridge English Dictionary, Cambridge, Cambridgeshire: Cambridge University Press, 1999–present.