Other forms: wake-up calls
When you stay in a hotel and need to rise early in the morning, you can request a wake-up call, when an employee telephones at a specific time so you don't have to set an alarm.
A wake-up call is exactly what it sounds like, a ringing phone that acts as an alarm. You can arrange for a wake-up call when you're traveling, or ask your friend for an informal one on the mornings you both wake up early to go for a run. A figurative wake-up call is a sudden, clear warning that something bad is going on: "All those cavities were a real wake-up call about eating so much candy."