Case 1: When I sleep slightly less than would be ideal, for example less than 7 hours per night, I wake up reasonably functional and get through the day without being excessively tired, if not being totally alert either.
Case 2: When I sleep slighly less than would be ideal, for example less than 7 hours per night and wake up, let the dog out to the backyard, wait a few minutes, let the dog back in, and decide to go back to sleep because it’s weekend. Now falling asleep takes a while but eventually I succeed. Then after an hour or two at max, I wake up again, but this time around I’m extremely drowsy with muscles aching and it takes serious effort to get up and get the engine running at normal speed. Even though the total amount of sleep (about 8-9 hours) sounds pretty ideal on paper.
Why is that?
I can’t nap, it always makes me more tired. Long or short, it never helps.
7 hours is fine, if you wake up rested then 7 hours is perfect for you, and it’s sufficient. I like 7.5, anything over 6 hours and under 10 is normal as far as I know.
And as others are saying, waking up in the wrong part of the cycle, it’s disorienting and feels like you got less sleep. This happens to me all too often.