PHBefore alarm clocks, there were alarm humans
The job of knocker upper (yes, that's really what they were called) originated in Britain during the Industrial Revolution, when people needed to wake up and get to work, but alarm clocks were not accessible to the general population.
A knocker upper's job was to literally take a wooden stick and knock on the door to make sure you'd wake up—just two to four knocks, and then they were on their way, no sticking around. Some even used pea-shooters to shoot dry peas at tenants on higher floors, in order to wake people up on top floors if stairs were not accessible.
(s) bestlifeonline