> Deep sleep is not improved by consistent sleep/wake times, and adjustments to noise/temperature/light conditions?
Deep sleep definitely benefits from consistent sleep/wake times. Your body tries to play catch up if you break from your normal rhythm but itβs not entirely effective.
I think the parent comment might be exaggerating the futility of sleep hygiene because they have a product to sell. :) Proper sleep timing, duration, and sleep hygiene are inarguably valuable for proper sleep architecture.
I'm not saying sleep hygiene is futile, I specifically say it is important, and sleep hygiene improves the potential for deep sleep, it does not directly improve deep sleep.
Sleep hygiene impacts sleep duration, which can impact all phases of sleep. It impacts the sleep phase potential, which is different from directly impacting sleep.
Measuring only sleep duration is like measuring only how much time you spent at the gym, ignoring what exercises, weights and reps you did.
(I don't have an answer to the overlap question; I'm squarely in Hard Fact.)