I'd like to see some deeper explanation around the following: > My average sleep efficiency (time asleep vs time in bed) according to Apple Watch & Oura is ~85

I'd like to see some deeper explanation around the following: > My average sleep efficiency (time asleep vs time in bed) according to Apple Watch & Oura is ~85%, meaning to get my 7h30 of sleep to feel rested I will stay more than 10h in bed. That sucks! 1. Where does the 10h figure here come from? It seems to me that 85% SE would reach 7h30 sleep hours at 8h50m bed hours (7.5/0.85). 2. What is an expected healthy sleep efficiency? Does 85% fall outside the normal range? 3. Where does the 7h30 target come from? If this is based on the standard adult recommendation of 7-8 hours, are we sure that this recommendation assumes 100% SE? If it doesn't, we're mixing different units.