wait up
US /weɪt ʌp/
UK /weɪt ʌp/

1.
2.
quedarse despierto esperando, no acostarse
to stay awake, especially late at night, waiting for someone or something
:
•
I had to wait up for my brother to come home.
Tuve que quedarme despierto esperando que mi hermano llegara a casa.
•
Don't wait up for me, I might be late.
No me esperes despierto, podría llegar tarde.