Every morning, before we have decided anything about the day, light has already started deciding for us. It sets a clock, nudges hormones, shapes mood, and gets the body ready for the night that will come many hours later. Most of this happens without our noticing. This piece follows that path from the horizon to the brain. It traces how light gets in, what it changes along the way, and why the soft hours near sunrise and sunset sit at the center of the Sungazing Protocol.
A word on method before we begin. Much of what follows comes from studies of lamps, light boxes, LED panels and medical lasers, where researchers can control the wavelength, strength and timing. Sunlight is not a lamp. When a finding comes from a device, I say so. When something is claimed for sunlight itself, I try to say how strong that claim really is. Where the evidence is thin, it is better to stay honest than to sound certain.
Part One: The Doorways
The eye is a piece of the brain
We tend to think of the eyes as cameras that send pictures back to the brain. In fact, the retina grows out of the developing forebrain. It is brain tissue that has moved forward to meet the world. Seen that way, light reaching the eye isn't just reaching a sense organ. It is touching the nervous system directly.
The retina has two jobs. The first is the familiar one, seeing. Rods and cones turn light into the images, colors and edges we use to read a page or recognize a face. The second job is quieter. It doesn't build pictures at all. It measures how bright the world is and reports that to the parts of the brain that keep time.
The cells that tell time
That second job belongs to a small group of retinal cells called intrinsically photosensitive retinal ganglion cells. They contain a light-sensitive pigment called melanopsin. David Berson and colleagues described how these cells set the circadian clock in 2002. Their nerve fibers run along a dedicated route, the retinohypothalamic tract, to the suprachiasmatic nucleus. This is a cluster of roughly 20,000 neurons in the hypothalamus that acts as the body's master clock.
From there, the clock coordinates a daily program: when cortisol rises, when core temperature climbs and falls, when we feel hungry, and when melatonin is released. Left without strong light cues, the human clock tends to drift on a cycle a little longer than 24 hours. Daylight is what pulls it back into line each day.
Melanopsin is most sensitive to blue-cyan light, around 480 nanometers. Researchers led by George Brainard showed in 2001 that the wavelengths best at suppressing melatonin in people match melanopsin's sensitivity. This detail matters later, when we come to the colors of the low sun.
The skin is a second doorway
The eyes are not the only way in. Skin responds to light too, through routes that have nothing to do with seeing. Ultraviolet B light on bare skin starts the chemistry that makes vitamin D. Ultraviolet A can release stores of nitric oxide from the skin into the blood, which relaxes blood vessels. Richard Weller's work in Edinburgh suggests this effect on blood pressure is separate from vitamin D and from heat.
Longer wavelengths go further still. Red and near-infrared light can travel well past the skin's surface. Work from Glen Jeffery's laboratory at University College London has measured near-infrared light in the 830 to 860 nanometer range after it passed all the way through the human chest. A small fraction gets through, but it is measurable. Clothing dims it without stopping it entirely.
So light reaches us through two doorways: the eyes, which report to the brain, and the skin and deeper tissues, which respond more locally. Both matter. They are not the same thing, though, and much of the confusion about light and health comes from blending them together.
Part Two: Setting the Clock
Morning light and the cortisol rise
The morning signal does its most important work through hormones. Cortisol is usually described as a stress hormone, but a healthy rise soon after waking is a normal part of starting the day. It sharpens alertness and gets the body moving. Bright light in the eyes early in the morning, roughly within the first hour after waking, appears to help anchor that rise in the morning, where it belongs. Without enough morning light, the peak may drift later, and stress responses through the day may run larger and longer than they need to.
A well-timed morning peak is linked to a low point in the evening. That evening low makes room for the hormones of sleep. Morning light has also been linked to better immune readiness, steadier metabolism, mood and learning. Those are broad associations, not guarantees for any one person, but they point the same way.
How bright is bright enough? Ordinary indoor lighting usually measures somewhere between 100 and 500 lux. Resetting the clock strongly through melanopsin seems to need something closer to 1,000 to 2,000 lux at the eye. Outdoor shade often gives 10,000 lux or more, and direct sun can give many times that. Roughly fifteen minutes outdoors within the first hour after waking is one commonly cited target. Older adults seem to benefit particularly. Clinical studies at the University of California, San Diego, led by Sonia Ancoli-Israel, found that bright light could improve sleep efficiency and steady the daily rest-activity cycle in older people. The lens of the eye yellows with age and lets through less short-wavelength light, which may be part of the reason.
Cloudy days, glass, and lamps
Clouds don't cancel any of this. An overcast morning is still far brighter than a lit room at night, and the clock still reads it. The habit worth building is getting daylight into the eyes, not waiting for a clear view of the sun.
Glass is a different story. Windows and windshields cut the light that reaches the eye, so stepping outside or opening a window works far better than sitting behind a pane. For people who wake long before sunrise, or who live through long dark winters, a light box of about 10,000 lux is a well-established substitute. The effect also seems to build over time, so a missed morning can be partly made up with a longer session the next day.
Screens are one more piece of the picture. They are far too dim to stand in for morning daylight, but they can be bright enough at night to push cortisol up and hold back melatonin. That is exactly the wrong way round.
From serotonin to melatonin
The clock's signal doesn't stop at the hypothalamus. The same light pathway branches toward the raphe nuclei, the brainstem centers that make serotonin. In 2002, Gavin Lambert and colleagues sampled blood leaving the brain and found that serotonin turnover rose with the amount of bright sunlight on the day of sampling, regardless of season or temperature.
Serotonin is also the raw material the pineal gland uses to make melatonin. So the day and the night are connected. The light we take in during the day supports serotonin, and serotonin later becomes the night's sleep signal.
Part Three: The Pineal Gland, Plainly
The pineal gland attracts more myth than almost any other part of the brain, so it is worth being clear about what it actually does.
In many fish, amphibians and reptiles, the pineal is directly sensitive to light, and some species even have a light-sensing "third eye" on top of the head. Mammals lost that ability. In us, the pineal has become a dedicated night-signal gland, and the work of sensing light moved into the eyes. Light doesn't land on the human pineal. It lands on the retina. The retina informs the master clock. The clock sends signals down through the spinal cord and back up through a nerve in the neck. At night, that nerve releases norepinephrine onto the pineal cells, which then turn serotonin into melatonin.
Melatonin is the body's darkness signal. It falls when light reaches the eyes and rises in the dark, carrying the night into sleep, the nightly drop in body temperature and the timing of many other systems. Alfred Lewy and colleagues showed in 1980 that bright light at the eyes suppresses melatonin in humans. Melatonin also acts as an antioxidant. Some is made in cells throughout the body, not only in the pineal. Research from the Jeffery lab suggests that long-wavelength light may help release this stored, protective melatonin within cells. That idea is still developing.
The pineal also tends to collect calcium deposits with age, sometimes called brain sand. A 2023 review of imaging studies by Belay and Worku estimated that somewhere around six in ten people show some pineal calcification, with wide variation between studies. In a small 1999 study of 26 people, Kunz and colleagues found that people with more uncalcified pineal tissue produced more melatonin. Reviews by Tan, Reiter and colleagues link heavier calcification to lower melatonin and, possibly, to sleep problems and some age-related brain disorders. They are careful to say that cause and effect haven't been established. A calcified pineal is not a diagnosis, and it is not a proven cause of depression.
One point deserves to be stated firmly: light entering the eyes doesn't shine on the pineal or "decalcify" it. The connection is entirely through nerves and hormones. The pineal hears about sunrise secondhand.
Part Four: Mood and Mental Health
For many people, the clearest benefit of light is in mood. Low mood that arrives with the short days of winter responds to bright morning light well enough that psychiatry treats light as a genuine therapy. A 2005 meta-analysis by Robert Golden and colleagues in the American Journal of Psychiatry found bright-light treatment effective for seasonal depression, with a smaller benefit outside the winter months. In a 2016 trial in JAMA Psychiatry, Raymond Lam and colleagues found that 10,000 lux light therapy improved non-seasonal major depression compared with placebo.
These studies used light boxes, not the sun. They are still a strong reminder of what morning light can do for the mind, and the lamps themselves were designed as stand-ins for a bright morning sky.
The pattern of light across the whole day seems to matter as much as any single dose. A large analysis drawing on the UK Biobank, a database that follows hundreds of thousands of people, found that bright days and dark nights each relate to better mental and physical health, and that the benefits add together. People with more light exposure at night had a noticeably higher risk of early death. Light at night is not a harmless convenience.
For the author of these books, sunrise and sunset have been the most important part of a mental-health routine. That is a personal account, offered honestly, not a clinical claim. It does sit comfortably beside the research on clocks, serotonin and seasonal mood.
Part Five: Sleep and the Evening
The clock shapes the night as much as the day. A striking demonstration came from Kenneth Wright and colleagues in 2013. They took people camping in the Rocky Mountains with no electric light. Within about a week, the volunteers' melatonin release and their sleep had shifted earlier, back into step with sunset and sunrise. Electric light had been holding their nights late.
Evening daylight seems to have a protective role too. Getting some natural light into the eyes in the late afternoon or around sunset, without sunglasses, appears to make the light-sensing cells of the eye less reactive to artificial light later on. If so, evening screens and lamps do less to suppress melatonin or disturb sleep and blood sugar. This buffering doesn't seem to protect teenagers in the same way, which is one more reason to keep screens out of young people's late evenings.
Regular use of bright devices from early evening onward may put many of us in a pattern similar to that of shift workers, a group with well-documented problems with metabolism and long-term health. Darkness at night is half of the healthy rhythm.
Part Six: Learning, Energy and the Mitochondria
Why the brain cares about energy
The brain is an energy-hungry organ, and the retina is among the most energy-hungry tissues in the body. Photoreceptors are packed with mitochondria, the small structures inside cells that turn fuel into usable energy. That makes them powerful, but also vulnerable to oxidative stress as they age.
What red and near-infrared light do in the lab
An enzyme inside mitochondria, cytochrome c oxidase, absorbs light in the red to near-infrared range. The working idea in this field, often called photobiomodulation, is that the right dose of long-wavelength light can help mitochondria that have declined to produce energy more efficiently. Nearly all of the evidence below comes from controlled devices.
- Color vision in older eyes. In studies led by Harpreet Shinhmar with Glen Jeffery, adults over about 40 who had brief exposures to deep red light at 670 nanometers showed better color-contrast sensitivity, especially on the blue-yellow axis. In a 2021 study, a single three-minute morning session improved color contrast for up to about a week, and the benefit appeared when the light was given in the morning. The timing seems to matter. The eye appears to respond differently at different times of day.
- Light through the body. In a 2025 study from the same research line, a controlled 15-minute dose of 850 nanometer light on the back improved color contrast the next day. This happened even in a small group whose heads were wrapped in foil so no light reached their eyes. The sample was modest, so the authors' reported improvements should be read as early findings, not as a promise.
- Blood sugar. Michael Powner and Glen Jeffery reported in 2024 that 15 minutes of 670 nanometer light lowered the overall rise in blood glucose over two hours in a glucose tolerance test, by about 28 percent, and trimmed the peak.
- Retinal disease. Double-blind trials in dry age-related macular degeneration, known as LIGHTSITE II and III, used clinical devices with several red and near-infrared wavelengths. They reported benefits over sham treatment. These were diseased eyes treated with medical equipment, not people sitting in the sun.
Circulation and inflammation
Other groups have looked at blood flow. Lab work at the Medical College of Wisconsin found that red and near-infrared light helped restore healthier blood flow in diabetic mice. It seemed to do this by prompting blood vessel linings to release nitric oxide, a molecule that relaxes vessel walls. Human vessel cells in culture responded the same way. In a small randomized study of 20 healthy adults at the Hebrew University of Jerusalem, five minutes of near-infrared light on the wrist increased small-vessel blood flow by roughly a quarter, and by about half twenty minutes later. Plain red light did not do the same, and responses varied from person to person.
Reviews of exercise studies point in a similar direction. One analysis from Nove de Julho University in São Paulo pooled 13 trials and found modest gains in endurance and repetitions when light was applied before exercise. Another from Taipei Medical University pooled 24 studies and reported less soreness, faster strength recovery and lower levels of creatine kinase, a marker of muscle damage. A small trial in hip-replacement patients found that a single laser session after surgery lowered two inflammatory markers and reduced pain. That trial used a laser far stronger than any home device.
For people using panels, studies have typically used distances of about 6 to 12 inches, sessions of 10 to 20 minutes, and three to five sessions a week, with changes showing up over four to eight weeks. Panels used near the face call for proper protective eyewear.
What this does and doesn't say about sunlight
Here is where it is important to keep things separate. The low sun is rich in red and near-infrared light, and greenery reflects those wavelengths too. That is why shade under a tree feels cool and why time in nature bathes the body in long-wavelength light. It is reasonable to think that sunlight delivers some of the same wavelengths these studies used. But none of the studies above tested looking at the sun. The doses, wavelengths and timing were set by machines. The vision studies in particular used a controlled red light source, not the solar disk. Whatever benefit sunlight on the skin may bring, these trials don't show that gazing at the sun improves vision or brain function.
Shorter wavelengths have their place as well. Ultraviolet B on the skin makes vitamin D, and moderate exposure has been associated with healthier sex-hormone levels in both men and women. The goal is balanced, full-spectrum light, never so much ultraviolet that the skin burns. Some researchers are also concerned that hours under indoor LED lighting, which carries little red or near-infrared light, may be harder on mitochondria. That evidence is still early.
Part Seven: The Low Sun and the Safe Hour
Why the horizon is different
When the sun sits near the horizon, its light crosses far more atmosphere, close to 38 times the overhead path at the horizon itself. Along the way, shorter wavelengths scatter out of the beam. This is Rayleigh scattering, and it is why sunrise and sunset glow red and gold. Ultraviolet is reduced too, so the UV index is usually much lower just after sunrise and just before sunset. The sun's disk delivers far less energy at the ground than it does at noon, which is why a red sun can look gentle while the noon sun is blinding.
That advantage fades quickly as the sun climbs. Within twenty minutes of sunrise at some latitudes, much of it is already gone. Cloud, altitude, snow and desert air all change the picture. And redder doesn't mean harmless. The sharp central part of the retina, the fovea, can still be injured by an intense, focused image, and infrared heating is reduced at the horizon but not removed.
There is a quiet irony here. Melanopsin responds best to blue-cyan light, and the low sun is relatively poor in that band. Dawn light still sets the clock, because even a reddened sky is far brighter than a bedroom. But for the clock alone, a bright sky a little later in the morning, without looking at the sun, may actually be the stronger signal. The beauty of the red disk and the best stimulus for the master clock are not quite the same thing.
There is a second limit. The low sun doesn't make vitamin D. When the UV index is below about 3, the skin's vitamin D production is small, and dawn and dusk sit well below that. Vitamin D comes from higher sun on the skin, in measured amounts. It does not come from the gazing hours.
The Sungazing Protocol
The Sungazing Protocol, as it is described on the author's site, is simple and strict. Practice only during the first 45 minutes after sunrise or the last 45 minutes before sunset. Begin with 10 seconds, and add 10 seconds with each session. Never go beyond 44 minutes. Stop at the first hint of pain, squinting, headache or lingering spots. Those are signs of injury, not signs of progress.
The site also describes how varied practice is. Many people sit facing the rising or setting sun with their eyes closed. Some sessions last less than a minute. Others use sunlight only for the skin. The method above is the app creator's own. It is shared for information, not as medical advice, and practice is entirely at one's own risk. The author reports years of regular eye examinations and retinal photographs with no sign of solar retinopathy. One person's healthy eyes, though, don't prove the practice is safe for anyone else. Medical authorities generally advise against looking at the sun with the naked eye at any time of day.
It helps to remember that nearly all of the brain benefits described in this piece come from daylight reaching the eyes and skin. Clock setting, serotonin, mood, sleep and long-wavelength light on the body don't require looking at the sun. Facing the low sun, with the eyes open or closed, is a way of meeting that daylight at its gentlest.
Part Eight: Light Across a Lifetime
The longest view comes from Sweden. One study there found that people who got more sunlight tended to live longer. One finding is hard to forget: smokers with plenty of sun exposure outlived non-smokers who got little. That isn't a reason to smoke. Smoking remains one of the most damaging things a person can do. For anyone who has quit, it reads as two lessons in one: put the cigarettes down, and go outside.
Add the UK Biobank finding about bright days and dark nights, the evidence on light and mood, and the slow effect of light on sleep and metabolism, and a picture comes into view. Over a lifetime, a daily rhythm of strong daylight and real darkness seems to be one of the simplest supports we can give the brain.
Practical Takeaways
- Get outdoor daylight into your eyes within the first hour after waking. About fifteen minutes is a reasonable aim, and cloudy days still count.
- Step outside, or open a window. Glass blocks much of the signal.
- If you miss a morning, stay out a little longer the next day. In dark seasons, a 10,000 lux light box is a well-supported substitute.
- Get some natural light again in the late afternoon or around sunset, without sunglasses, before evening screens.
- Keep nights as dark as you can, especially for children and teenagers.
- Let light reach your skin a few times a week in measured amounts, never to the point of burning. Remember that vitamin D needs higher sun, not the gazing hours.
- Spend time among trees and greenery, which bathe the body in long-wavelength light.
- If you use a red or near-infrared panel, follow the ranges used in studies and wear proper eye protection.
- If you choose to practice sungazing, follow the Sungazing Protocol exactly as written and treat any discomfort as a stop sign.
A Safety Note
Looking at the sun can cause solar retinopathy, a burn of the central retina that can be permanent. Damage has been reported after only seconds of exposure under some conditions. If you choose to look toward the sun at all, do so only during the low safe hours: the first 45 minutes after sunrise or the last 45 minutes before sunset, when the light is soft and the UV index is low. Never look at a bright, high or painful sun. Stop immediately at any discomfort, glare, squinting, headache, watering or lingering spots, and don't push through. Never use binoculars, telescopes, camera viewfinders or any other optics, and never look at an eclipse without proper solar filters. Children and teenagers, people who have had cataract or laser eye surgery, people with existing eye or retinal conditions, and anyone taking medication that increases sensitivity to light should talk to an eye doctor before trying any form of sun viewing. Most of the benefits in this piece come from daylight in general, not from looking at the sun.
This piece is for general information only and is not medical advice.
