stay up until (some hour)

stay up until (some hour)

To remain awake until some time, especially when it is past one's usual or required bedtime. I had to stay up until nearly 1 AM last night doing my taxes because I left them until the last minute again. We let Johnny stay up until midnight last night so he could do the New Year's Eve countdown with us.
See also: stay, until, up

stay up until

a particular time to remain awake and out of bed until a particular time. I stayed up until long past midnight last night. Do you think Susie should stay up until midnight?
See also: stay, until, up