Deep sleep is not improved by consistent sleep/wake times, and adjustments to noise/temperature/light conditions? If not, which sleep phases are?
(I don't have an answer to the overlap question; I'm squarely in Hard Fact.)
(I don't have an answer to the overlap question; I'm squarely in Hard Fact.)
Deep sleep definitely benefits from consistent sleep/wake times. Your body tries to play catch up if you break from your normal rhythm but it’s 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.
Measuring only sleep duration is like measuring only how much time you spent at the gym, ignoring what exercises, weights and reps you did.