Here's the distinction almost no doctor explains, but is absolutely critical for women over 40, their metabolic health, mitochondria, sleep, and sunlight. THE TWO TYPES OF MELATONIN 1. Brain (Sleep) Melatonin 2. Mitochondrial (Internal) Melatonin Most people only know about the first kind…But it’s the second kind that changes everything about inflammation, aging, hormones, and chronic fatigue. SLEEP MELATONIN (The one you already know) Where it’s made- A tiny gland in your brain called the pineal gland. When it’s made- At NIGHT , only after your eyes see darkness and your brain senses that the sun has gone down. What triggers it- - Sunset light (orange/red wavelengths) - Darkness - A healthy circadian rhythm - Low nighttime blue light (Screens, house lights) What it does- This type of melatonin is like your sleep switch. - Helps you fall asleep - Helps you stay asleep - Lowers core body temperature - Signals the brain that the day is done - Supports REM and deep sleep cycles How artificial (blue) light hurts it - Phones, laptops, TVs, LEDs, and indoor lighting block pineal melatonin production. This is often why people feel- - Wired at night - Tired in the morning - Poor recovery - Middle of the night wakeups But sleep melatonin is only 5% of the total picture. The other 95% is WHERE the magic happens. INTERNAL MELATONIN (MITOCHONDRIAL MELATONIN) (The one almost nobody talks about) This is the melatonin your cells make internally, especially your mitochondria, the little engines that make ATP (energy). And here’s the big difference: This melatonin does NOT depend on darkness. It is made from sunlight exposure, especially- - Near-infrared (NIR) light - Red light - A portion of UV light These wavelengths are present in morning sunlight, midday sunlight, and late afternoon sunlight. So, You create most of your melatonin during the day, from sunlight, NOT at night from supplements or darkness.