I did an accidental retreat by attempting to climb the Cotopaxi volcano, in Ecuador.
Lodged at "Secret Garden". To our suprise on arrival, they had no wifi and we could not get cell tower signal. So we had to find other ways to be entertained. They helped: activities + daily group hikes and mountaneering trails that are bound to leave you ready to crash by 8pm. We are not big hikers, in fact we hike at most 3 times per year - but we found that the combination of peer pressure, adventure/adrenaline plus the need to do something kept us going on daily treks.
1-2 weeks of that and you could be forming a positive routine. At least you will be rested.
PD met an SRE from Netflix there. He successfully summitted the Cotopaxi. We hiked it... but did not try to summit due to difficulty + sleep deprivation requirement to make an attempt :)
But it's not the place for cerebral activity, where things works best after hours.
I guess in the end it's a matter of performing well under distractions or not. I often found that the reason for late night performance was due to the lack of interruption and all sorts of external stimulation that goes with daytime.
Now I wish I could find a middle ground.
But I started exercising during the pilgrim days, mornings, and the habit stuck but now I do evenings. I feel most productive now between 8am-noon, even with people around.
There was a job change too though, so can’t guarantee it was the exercise that changed things. Exercise was definitely a massive net benefit either way though.
I go really hard with kettlebells for about an hour/day. Very low-impact, no stress to the joints, loads usually not heavy enough to cause severe muscle failure. Cardiovascular/aerobic state is similar to running, climbing stairs, swimming, etc. The exercises are all compound, and there’s enough resistance to build a good amount of muscle too (kettlebells go up to 200lbs).
Flexibility too, most of the motions involve stretching from the hips in one way or another.
And all you need is a living room and a kettlebell.
I feel like I found the holy grail of exercising, so I take every opportunity to recommend it. Google Pavel’s Simple and Sinister routine if interested, or check out /r/kettlebell. I add overhead presses and standing rows, a lot of people add snatches and cleans. Always new things to try. It’s fun.
Then one day I moved to a house that had no internet, and we would have to wait a month to have satellite put in, and we had no smartphones
After 20+ years of just thinking I had a sleeping disorder, losing internet access and living like a pilgrim caused my sleep schedule to naturally coincide with the setting and rising of the sun
Without any deliberate effort from myself whatsoever, I would get sleepy at like 9pm, and wake up around sunrise, wide-eyed and ready to start the day
I thought I had tried everything too, including screen limitations and so on. That probably didn’t work because just the awareness that I could go online if I wanted was enough to keep me awake, feeling like there was a party going on that I wasn’t there for. And of course I would cheat some days, and doing that even occasionally was enough to reset my progress to zero.
There’s probably some kind of “disconnection retreat” nearby you could try, where people get together in some remote place and stay off tech for 7+ days. Could be a fun way to see if this is the cause of your sleep issues.