@Joseph
I manage well on 4 hours per night. My parents had similar sleep patterns as do my brothers. My elder sister requires 7 hours.
The 4 hours is an every night thing. When I was younger I could skip a night’s sleep each week without it affecting me, but since about the age of 50, I need to sleep every night.
I always found the hour of 5:15-6:15 to be ‘my time’ and very productive, no interruptions.