Force yourself to stay up later to change the pattern?

It sounds like your body feels well-rested after 7 hrs of sleep, which is a normal and healthy amount of sleep for many adults. Perhaps forcing yourself to stay up til like 10pm for a night or 2 in a row could yield you sleeping til like 5am. Depending on how sensitive you are to caffeine, try drinking it til 10am or noon, or keep bright lights on a couple of hours later, play energizing music, do whatever it takes :) I hope it helps! Maybe try this before a do-nothing day, or experiment with it over an entire blocked-off weekend, so that in case it doesn’t work, you won’t have to be exhausted for a busy day!