Fascinating fact: the phrase "knock up," as in awaken by knocking, comes from the industrial revolution, after people were having to rise at a certain hour for the first time in history, but before the invention of the alarm clock. The "knocker-upper" was a person who went round with a long wooden pole, knocking on the windows to get people out of bed for their factory shifts.

https://en.wikipedia.org/wiki/Knocker-up