I read somewhere once that the body sleeps in 90-minute cycles (approximately). The first half hour, you descend into deep sleep. The middle half hour you’re in deep sleep. The last half hour, you come out of deep sleep. Lather, rinse, repeat for your entire time asleep. As such, I can see it making sense that if you go beyond 20 minutes, you do more harm than good, because you’re shocking your body out of deep sleep to a state of awakeness that it doesn’t want to handle.
I wish I could remember where I saw that. Sorry I can’t provide backup other than my memory.
I read somewhere once that the body sleeps in 90-minute cycles (approximately). The first half hour, you descend into deep sleep. The middle half hour you’re in deep sleep. The last half hour, you come out of deep sleep. Lather, rinse, repeat for your entire time asleep. As such, I can see it making sense that if you go beyond 20 minutes, you do more harm than good, because you’re shocking your body out of deep sleep to a state of awakeness that it doesn’t want to handle.
I wish I could remember where I saw that. Sorry I can’t provide backup other than my memory.