This is a somewhat bizarre scheduling method that only works for a few select people, but if it works for you, you'll achieve uncommon amounts of productivity in a single day.

Most people are monophasic sleepers, meaning they get their daily sleep in one chunk (or phase). Biphasic sleepers get their sleep in two smaller chunks, such as 4 hours in the morning and 4 hours in the late evening. Polyphasic sleepers take this method to the extreme, breaking up sleep into multiple short phases, which allows for less sleep overall and significant increases in productivity. The amount of sleep in each phase can vary, with some people sleeping only in 20-minute naps and others grabbing larger chunks of sleep and then supplementing with naps.