I think It’s depends on the person , nobody knows exactly , i myself if i sleep more that 7 hours i wake up feeling depressed, anxious, cranky etc, i can’t not even be on bed after 6 am , and i go to bed at 12 or 1 am. But if i sleep between 5 to 6 hours i wake up feeling better and happier, with more energy . Sometimes i have a party the night before and i get drunk and i go to bed late , and i only sleep like 3 hours , i wake up feeling amazing . So it’s all perspectives
It's possible you may have the DEC2 gene mutation, which would allow you to feel rested on 5-6 hours of sleep. Whether you still feel good on 5-6 hours when you're in your 40s... only time will tell.
Daniel Rodriguez