the morning after (the night before)
A hangover. A: "Ugh, I feel so sick." B: "Sounds like the morning after the night before to me. Weren't you out at the bar last night?"
morning after (the night before)
a hangover; the feelings associated with having drunk too much alcohol. Do worries about the morning after keep you from having a good time at parties? She's suffering from the morning after the night before.