Apple health sleep duration, 6pm-6pm

Apple health calculates sleep duration from 6pm-6pm instead of the actual duration.

I don’t know how to change it.

Nov 17 I slept 12pm-12am.

That’s 12 hours but it shows as 8 hours.

It cuts off at 6pm and applies the rest to the next day.

Theres no way for me to simply download the data and make my own graph to see trends either.