non-24-hour sleep–wake disorder is the official diagnosis for perpetual jet lag, or the 25+ hour day. it's when your circadian rhythm is out of sync with the time of day. someone with non-24 might sleep about an hour later than the day before, as opposed to sleeping every night and waking up every morning. non-24 is most common in blind folks, though sighted folks (like myself) can have it too. you're more likely to have it if your family also has unconventional sleep schedules.

another way to describe it is a "revolving sleep schedule." if you keep track of your sleep in a spreadsheet program like i do, with each sheet representing a week and black cells representing time slept, you might notice the sheets look like a barbershop pole: circling back to where you started over the course of a couple weeks.