Test out what happens to you when you alter sleep habits. How much uninterrupted sleep do you prefer and when? What are the effects of naps during the day on metrics you care about? Keep the traditional sleep log, and track your other related behaviors & habits like eating/nutrition, exercise, etc. National averages are useful, but nothing beats learning how our own bodies function in various situations.

Here is one example paper https://www.ncbi.nlm.nih.gov/pubmed/28545315 and while it isn't a direct example of how to find your own ideal sleep patterns, it does highlight the relationship between sleep and body weight in the study population and it again mentions the 6-8 hour recommended minimum sleep period. This source might be better https://www.sleepfoundation.org/excessivesleepiness/content/...