Used to be 9h per day for decades. Any more and I'd feel strangely groggy (unproductive), my body cannot deal with oversleeping. Lately I experimented with a 1

Used to be 9h per day for decades. Any more and I'd feel strangely groggy (unproductive), my body cannot deal with oversleeping. Lately I experimented with a 1h nap after lunch (I'm getting old!), and can report that I feel equally refreshed with only 6h of sleep a night. So, 7h total now, but split into two 1+6 sessions. It feels great to have 2 extra hours per day!