There's a huge difference between 7 hours of straight sleep which your body decides when to wake up from, and 7 hours of fragmented sleep which is constantly interrupted at the worst possible time. Every single night.
One secret that seems worth trying for everyone is to go to sleep at 9 PM and wake up at 3-4 AM.
Get a few hours before anyone wakes up, and the best uninterrupted sleep for the most part, and the sleep before midnight has a magnified and compounding effect.
Also early morning is at least 2x as effective energy and clarity wise as late nights.
I've experimented with sleep schedules a few times. If I go to bed before I'm ready I will not sleep very much at all. Best for me is when I go to bed at roughly 1am and wake around 7am. If you want me awake at 3am, I will need to stay up that late. As I learned resetting myself after overnight shifts, no matter how early I go to bed, I will not be functional at that time.
It's very possible it's not the same for everyone. The circadian rythmn is universal though, and no human is really excluded from it. There might be a shift from it for some but verifying it is the important part to remove guesswork.
It also seems the case that sleep adjustments, in any direction, don't happen over night.
Consistency is the most important thing no matter what anyone does.
Agreed that being woken up is very stressful, but I suspect it's more the stress that's exhausting than the decrease in sleep itself. I'll share a personal anecdote: A few years back I had trouble sleeping, sometimes I'd wake up multiple times and spend 4 hours awake staring at the clock and only sleep 2 or 3. Eventually I figured that as long as I laid in bed and was somewhat relaxed, I could still function the next day, the actual sleep time didn't make that much of a difference. I also didn't drink coffee or take any stimulants to stay awake or anything like that. The problem went away when I moved out of the city after a year or so, some mild allergy I had went away as well. I'm not claiming it's scientific or anything, just sharing my experience.
Get a few hours before anyone wakes up, and the best uninterrupted sleep for the most part, and the sleep before midnight has a magnified and compounding effect.
Also early morning is at least 2x as effective energy and clarity wise as late nights.