Okay, it's more of a cheeky answer than a real "clinic," but the logic is there. You see, when you sleep, your body goes into "sleep mode" with an emphasis on repairing and restoring virtually every cell in your body – so closing your eyes properly is essential for brain function, immunity, muscle repair, metabolic health, and a lot more. It has even been clinically shown to support longer lifespan, which is why Young files sleep in one of his aforementioned "longevity buckets".
In terms of how much sleep you can get over the threshold, it's not that dry – after all, everyone has a different ideal sleep schedule. "My rule is eight hours in bed, seven hours of sleep," offers Young. Still, he suggests choosing deep, quality sleep over quantity (because it's not just about clocking hours). “When people ask me what they can change in the next two weeks, I always advise them to walk on vegetables and get enough sleep both body and mind,” added Young. "The transformation that you can make in two or three weeks is really amazing."