You must not be aware of the research on Non-24[1] (or "Non-24-hour sleep–wake disorder") which OP seems to have (though perhaps they also aren't aware this is a thing).

Not saying non-24 is good for you, but for people unable to follow a 24-hour schedule, free-running sleep (which is what OP is doing) is vastly better than constantly pushing through sleep deprivation, when one's schedule allows for it.

Speaking as someone with non-24 myself (which is much more severe in the winter)

edit: after reading more closely, it appears OP has entrained to a 28-hour day rather than doing free-running sleep; 28-hour days are convenient in that the week gets sliced into 6 days and allows for a consistent weekly schedule. However, I suspect OP actually naturally gravitates towards a shorter day like 26 or 27 hours based on their napping patterns. I also wonder if they might even have more success with 24-hour days and regular exercise, as from their description it almost seems like the daily exercise practice which they started after the 28-hour day might be regulating their circadian rhythm to be closer to a natural day.

[1]: https://en.wikipedia.org/wiki/Non-24-hour_sleep%E2%80%93wake...

I did free-running sleep for a while (I mention this in the original 28h day post), but decided on 28h days to weekly match other people's schedules.

I exercised regularly before 28h days, and my sleep was still chaotic with that. I didn't exercise daily though, it was hard to fit everything I wanted to do on a 24h day. Having longer days means I can fit more things, which I think is one of the reasons why I increased the amount of exercise after moving to 28h.

I also haven't read any research on this, I just did what felt more natural and logical to me.

I miss being able to do free-running sleep.

I remember so many people in my life being skeptical about my claim that I naturally have longer days than 24h. Then ~6 years ago I actually tested it; my watch recorded my sleep, and it became obvious:

https://photos.app.goo.gl/rTh2vkEMPEiJXx5Y7 [time-asleep graphed on a daily 24h chart]

And only then did I learn what a non-24 was.

> imagine making every single day a jet-lagged day.

That's exactly what this pattern is trying to avoid. For people whose sleep cycle is longer than 24h, a "normal" rhythm makes every single day a jet-lagged day, and in the "wrong" direction (it's easier to travel west/stay awake longer rather than travel east/go to bed earlier for most people).

I did 36-hour days (awake for 24, asleep for 12) for a long time and it was fine. I'm unable to do so now, due to other obligations, but I still think it worked better for me than a 24-hour day. Even today I inevitably stay up all night, getting at most 1-4 hours of sleep, 2-3 times per week.

I don't see anything problematic with TFA's 28-hour days.

I lived on 36 hour days for a good year or so as well. It made being social very difficult, and was not the greatest thing for me overall, although I did get a lot of code written.

A few months ago I finally got a CPAP machine after getting a sleep study due to abnormal blood pressure patterns (my blood pressure wasn't dropping overnight on a 24 hour monitor). I can now wake up feeling alert and ready to go after 6 hours of sleep (even though I could use a little bit more); I haven't felt rested this way in the morning since more than 15 years ago in my 20s. I'm not particularly overweight, nor do I snore, so it's worth checking into if your sleep patterns tend towards abnormal.

I have slept 12+ hours less than a dozen times in my 40 years, and nearly every time was due to being sick. How did you manage to sleep so long?

Not who you are asking, but for me if there's no noise or activity in the house, I usually just keep on sleeping. 10 hours would be more common for me but I've done 12 hours pretty easily too.

I think I'm somewhere on the long right tail of needing a lot of sleep, I feel best with 10 but I can do with 8. Less than 8 and I don't feel too good.

In the winter I can do 12 hours pretty often. It's not always but every few years I get a few weeks or months of 12 hour nights.

I love sleep.

I have tried on occasion to work night shift. It is OK for a few weeks but within months I reach extreme exhaustion falling asleep while operating dangerous machinery, despite sleeping during the day. I experienced a similar phenomenon working on a fishing boat where I simply never adapted to sea sickness and after weeks of throwing up almost all food and fluids it took months to crawl back to activity and recover including the pneumonia induced from my immune system and homeostasis being beat down.

Human body can be really bad at adapting to unworldly environments to the point you totally break down.

I doubt your assertion about circadian rhythm research, largely because of the cave experiments that show that people naturally assume non-24 hour days when removed from sunlight and social cues.

The melatonin response to sunlight shortens the cycle so the oscillator runs long without it. It wouldn't work well the other way.

So, in other words, get more sunlight?

> I doubt your assertion about circadian rhythm research

You seem oblivious to the decades of research into chronobiology and studies into shift work, jet lag, etc.

Your loss.

Actually it's pretty in-line with it. Natural circadian rhythm is ~25hrs, with some individual variance, and it's easier to extend a circadian rhythm than shorten it. Jet lag research finds that flying west (lengthening), you can adapt at a rate of ~1hr per day. It's not crazy to think that someone might naturally be at 26-27hrs, then stretch it an hour each day no problem.