Kinda, yes. We have a circadian clock, a biological mechanism that works by releasing certain hormones over a 24 hour period, as well as taking external cues such as the Sun. Without external cues, the circadian clock can actually run a bit longer or shorter than 24 hours, and in babies it’s still all messed up (which is why they have an irregular sleep schedule).
Not just humans have a circadian clock, almost every animal does.
This has nothing to do with leap years though, since leap years just add a whole day, not messing with our circadian clock.