Tools that always work: are they being investigated? What are they?
You've discussed many tools to exercise more, lose weight, sleep better, and so on. In practice they're largely ineffective: they usually are a pattern of behavior that, if adopted and adhered to, will help address the issue. But there's no known way to reliably induce a desired change in behavior by "just doing it" or discipline or willpower. They're like abstinence-only approach to addressing the problem of unplanned pregnancies: no sex means no unplanned pregnancy. But obviously we know that it's horribly ineffective compared to modern birth control. So what are analogies for other issues? Let's take sleep. We know light and temperature are very important. Most importantly, many people have control over their environment (apartment/house and, especially, bedroom). When it comes to sleep going camping without electronics is pretty much the gold standard treatment. Exposure to light and temperature (+some other factors) are as good as they're even gonna get. Of course almost no one will live in a tent indefinitely. But imagine someone schedules the times (e.g. 6pm-5am?) when electricity doesn't work in his home: only the essentials like fridge, freezer, and the dimmest and warmest artificial light necessary for safety. Same deal with temperature: it'll either be equal to the outside temperature throughout the day or it'll be the same pattern but higher/lower by some constant for cold or hot times of year. Every morning the bedroom is lit up by bright and cold light. None of this can be changed at will. Any changes would require a visit by a professional that's at least a few days in the future. Is there any chance in hell this doesn't show clear improvements in sleep? Is there any way that compliance will be significantly higher than in any other method? It's just one hypothetical example so the nuts and bolts aren't important. My point is that researchers working on obesity, sleep, addiction etc. seem to lack urgency and vision to research and promote solutions that make significant changes in people's environment. Why? Obesity crisis should be a warning sign to everyone in different fields: nothing that relies on recommending individuals this or that diet or exercise regiment works. Nothing that requires discipline and self-control 24/7 can possibly work. People reach a breaking point, they indulge themselves, and that's often it, no matter how many times they try. Sleep (and some other areas) are different in that we can feasibly make changes in our environments that are immune to loss of self-control and which can be guaranteed to be in place long enough for someone to see the benefits. These problems are urgent and plenty of people have tries way, way crazier solutions. Why not focus on solutions which have to work instead? (Unless ~everything we know about the importance of light, temperature, and maintaining regular sleep rhythm is wrong – a fascinating, if unlikely outcome. Academics often talk about behavior patterns of modern-day hunter-gatherers or the Inuits or our ancestors to illustrate the way humans used to behave before we've become wealthy and technologically advanced beyond their wildest dreams. The answer is staring them right in the face but they don't notice it: what they did isn't what's important; it's what they couldn't possibly do no matter how hard they tried. Becoming obese would have been a big challenge even if the whole community offered their help and support. Imitating the sleep habits of a typical modern Westerner would have been impossible period. No amount of avoiding sunlight in the morning and exposing oneself to bright firelight could have come close to what we do when we're trying to limit our nighttime light exposure! No way to not experience the changes in the temperature within the day and over time. No way to amuse oneself with internet, tv, games, and podcasts when everyone else is asleep. That's what the solution looks and feels like. So why isn't it the starting point? Those issues are serious and they are urgent. Why is everyone trying to find "actionable" solutions whose effects are often hard to notice? Why not nuke the problem first and then try to figure out if we can use it some more precise weapon? Where's the urgency?
What factors affect duration of sleep
I have no problem falling asleep (usually within minutes) but I randomly get nights where I wake up in the middle of the night and just can't go back to sleep. I do daily morning sunlight viewing, stop caffeine ~8 hours before going to bed, workout, no food or bright lights for the last few hours of the day..etc but I get these random nights where I wake up and can't go back to sleep. You mention NSDR as a solution but i'm wondering if anything can be done to specifically improve sleep duration.