Thank you for the nicely illustrated post! That's what I had been doing for years - reducing my sleeping hours to prolong the time I could dedicate to work or study. I had to face the consequences later when my health issues started. Numerous researches show that a human organism can function well only when having enough sleep - that is, 8 hours for an adult. I stumbled upon an interesting research paper https://ivypanda.com/essays/the-eight-hour-dilemma-sleeping-time-reduction-when-a-single-hour-makes-a-difference-research-paper/ with an idea about the quality of sleep over quantity. While the eight-hour regime is considered optimal, it can no longer be the ultimate amount of time for a healthy sleeping regime. The author states: "...while ones might need eight hours of sleep, for others, seven hours can suffice, and some might demand nine hours according to their own bodily functions and features..." As for me, I still think eight hours of sleep are optimal, and I feel best when I manage to reach this amount of sleep nightly. Thanks again for the deep insight into the topic and the recommendations on stopping sleep procrastination.