Matthew Walker, PhD in his book "Why We Sleep" discussed sleep cycles and their variances from one person to the next. Specifically, during his discussion of circadian rhythm in chapter 2. From page 22: "As a social species, should we not all be synchronized and therefore awake at the same time to promote maximal human interactions? Perhaps not. As we'll discover later in this book, humans likely evolved to co-sleep as families or even whole tribes, not alone or as couples. Appreciating this evolutionary context, the benefits of such genetically programmed variation in sleep/wake timing preferences can be understood. The night owls in the group would not be going to sleep until one or two a.m., and not waking until nine or ten. [...] Consequently the group as a whole is only collectively vulnerable."

He discussed varying sleep cycles across individuals. Specifically, he suggested society needs to be more inclusive of different sleep patterns and needs. Instead, society rewards people who naturally wake early in the morning at the cost of "night owls". All in the same area of the book.

You're welcome to research and earn your own PhD in neurology and author your own book on sleep patterns, but I'll stick with Dr Walker's work.