Most people think melatonin is a simple “sleep hormone.” It is more interesting than that.

Melatonin is made in two main ways. At night your pineal gland releases melatonin into the blood to signal darkness. During the day many tissues make their own melatonin inside cells, where it helps neutralize oxidative stress and steady energy production.

Near infrared light, which makes up a large slice of natural sunlight, appears to support this daytime, tissue-level melatonin.

Put together, you want bright natural light by day and true darkness at night so both systems do their jobs.

What Melatonin Is & Where It Comes From

Melatonin is derived from tryptophan through a short enzyme pathway. The classic source is the pineal gland, which releases melatonin at night to reinforce your body clock. That explains the nightly rise in blood levels and the sleepy signal you feel after dark.

But melatonin is also made locally in the skin, the gut, and other organs. This cellular pool acts as an on-site antioxidant and signaling molecule. It often stays within the tissue where it is made and does not always show up in blood tests.

Here's a helpful way to think about melatonin:

• Pineal melatonin: the darkness signal that helps time sleep and recovery.

• Cellular melatonin: daytime production inside tissues that helps handle oxidative stress and preserve function.

How Light Shapes Melatonin Across the Day

Light is not one thing. Different bands have different jobs.

Bright visible light to the eyes in the morning anchors your circadian clock. Evening bright light suppresses pineal melatonin and delays sleep. Keeping evenings dim protects the darkness signal.

Near-infrared light during the day reaches deeper than visible light and can support local melatonin inside tissues, especially in mitochondria-rich cells. Natural daylight is loaded with NIR and even shaded outdoor spaces contain plenty of it.

The simple pattern is this: daylight first, darkness later. That rhythm lets pineal and cellular melatonin complement each other.

Melatonin's Role in Sleep Quality

Good sleep starts long before bedtime. Daytime behaviors set the stage for your pineal surge at night.

Get outside early

Ten to thirty minutes of natural light in the morning helps your internal clock start its countdown to nighttime melatonin. Outdoor light also contains NIR that you will not get from typical indoor LEDs.

Stack daylight throughout the day

Eat, walk, or take calls near a window or outside when possible. Shade counts. NIR scatters off surfaces and still reaches you.

Guard your evenings

After sunset, lower overhead lighting, use warmer bulbs, and keep screens farther from your face. The goal is to avoid suppressing pineal melatonin close to bedtime.

Where Near-Infrared Light Hits

Near infrared sits just beyond red light. It travels deeper into tissue and is abundant in sunlight.

Daytime NIR exposure aligns with higher local melatonin inside cells, which supports antioxidant defenses when metabolic demands rise.

That is one reason outdoor activity can leave you both pleasantly tired and ready for a solid night later. You are giving cells the inputs they need by day so the night signal can focus on sleep timing.

The Rise of Melatonin Supplements

Oral melatonin can help with jet lag or a shifted schedule. It is not a shortcut for daytime light and nighttime darkness, and higher doses do not mean better sleep.

If used, the smallest effective amount close to the target bedtime is usually the sanest approach.

Final Word

Sleep improves when your day and night tell the same story. Daylight, including near infrared, supports cellular melatonin and steady energy. Darkness lets the pineal surge guide you into deep, consolidated sleep.

Build your routine around that simple arc. Step outside early, collect natural light through the day, and make evenings dim. Keep the bedroom dark and cool.

With those basics in place your nights feel easier and your days feel stronger.

Resources

1. https://pmc.ncbi.nlm.nih.gov/articles/PMC9855654/

2. https://www.salisburypediatrics.com/post/near-infra-red-nir-light-and-health-a-big-deal

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