What is the origin of the idiom "the small hours" and when to use it?

The idiom "the small hours" has been in use for a significant period, and its exact origin is unclear. It has likely evolved over time through cultural and linguistic influences. The use of "small" in this context may have originated from the concept of the nighttime hours being perceived as shorter or narrower compared to the longer daylight hours. This expression is commonly used in both formal and informal language to specify a particular time period during which most people are asleep and the night is at its quietest.