A short YouTube monologue arguing that morning exposure to natural sunlight within the first hour of waking is the primary cue that sets the circadian rhythm: it suppresses melatonin and triggers cortisol production, which sets daytime alertness and leads to melatonin production again ~12–16 hours later to enable sleep.
Let's talk about the underrated secret. Your morning determines your night. The circadian rhythm is your body's internal clock. It runs on a 24 hour cycle and it controls your sleep wake patterns. And the biggest trigger for setting that clock? Light. More specifically, natural sunlight. In the morning, when your eyes register natural light within the first hour of waking, you send a signal to your brain to suppress melatonin, your sleep hormone, and start producing cortisol, your energy hormone. This one step sets your entire day in motion, and 12 to 16 hours later, your body starts making melatonin again to help you fall asleep.
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