There is a genetic mutation that a small minority carry that allows them to sleep less (6.2 hrs average). You simply may be one of those people.

Sleep duration is just a single metric; apnea, REM+NREM3 duration etc. all matter. You may be getting as much REM+NREM3 in 6.5 as someone gets in 8... and if you don't have apnea, you might get WAY more actual sleep than most people.

I went through a period where I believed my body would only accommodate a certain amount of sleep. Once I stopped caring about sleep duration... that duration slowly increased to eventually revert to 'normal'.

The key is to just _stop_caring_ about it. Do everything right, and let your body/mind handle the rest. It doesn't happen overnight.

> just _stop_caring_

I agree with this. Worrying about the quality of my sleep caused me more sleep problems than it solved. I quit tracking my sleep, I go to bed when I'm tired and get out of bed when I wake up. E.g. I don't try to keep sleeping just because it's 4AM. My sleep quality has steadily improved as a result. Just roll with it.

I’ve done this at times and it always wound up putting me out of phase with normal hours. That quickly causes all sorts of scheduling catastrophes.

I have however found that being a bit short on sleep one night and making it up another works perfectly fine if your weekly average comes out ok. Another thing all the sleep articles claims isn’t possible.

How do you check for whether you have this mutation? Sequence your genome? Any recommendations?

This seems to be a prime case of being misled that anything under 8 hours is bad. If you have no issues, 6.5 hours is a perfect amount with similar health outcomes to 8 hours across meta-analyses and all the Pop sleep science telling you that you need more is just adding needless sleep anxiety to your life in this case.

I thought 6-8 hours was considered the "normal" range, so there is nothing wrong with your 6.5 hours.

Maybe there is something I'm missing, but if you're not tired what is the problem?

> nothing more I can do

Notwithstanding everything else you said, you don't know that for a fact. Some unlikely interventions can have a massive impact. Even if you're content with your sleep it doesn't mean it can't be improved.