Your Body Already Knows What Time It Is We celebrate Biological Clock Day on April 28, and here's what ancient Ayurveda and modern neuroscience both agree we should be doing, and when. Your body runs on an internal 24-hour clock (circadian rhythm) that governs sleep, digestion, immunity, mood, and more. Remarkably, Ayurveda mapped this same system 5,000 years ago through its daily routine framework, Dinacharya. Modern life with late meals, excessive screen time, and inconsist