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Working Paper: Retinal Light Deficiency

Humans are diurnal creatures. Being a “diurnal creature” means that we’re most active during the daytime. But what if daytime never comes? Most people are not normally exposed to what could be considered “normal” levels of light exposure in the eyes, at “normal” times of the day. Let’s explore this a bit.

You can express light intensity in a unit called lux. In my home office, my light meter tells me that when I look at my computer screen with the overhead light on, the light intensity is about 25 lux. Okay. I can see everything in the room just fine. So what? Well, at sunrise on a sunny day, the same lux meter tells me the light intensity is 10,000 lux outdoors. And that can go to 100,000 lux at mid-day on a sunny day. If humans evolved spending most of their time outdoors, yet I spend most of my time indoors, could my body and mind be functioning as if there was no daytime? Has this gone on for the majority of years or decades?

Remarkably, bright light exposure seems to initiate a “boot-up” sequence for the human brain and body. Light goes into the eyes, hits the retina, which sends signals to the hypothalamus, which in-turn lowers melatonin secretion and elevates cortisol. These last two work to make you feel more energized, awake, and alert. But that seems to be just the beginning of the “boot-up” sequence. Over the past month, I have been exploring the scientific literature to understand what else happens during this sequence, and what happens to human health when it is not initiated.

I’ve made significant progress on what I am currently calling the “retinal light deficiency working paper”. Retinal light exposure apparently influences so many aspects of human health, that I am very excited at its possible implications. I’m going to refer to “light exposure to the eyes” as “retinal light exposure”, to distinguish it from light (UV) exposure on the skin, which is relevant for synthesis of vitamin D.

One of the “problems” I’ve been running into while writing this Working Paper is that, as I dig around in the research, number of aspects of the human experience that retinal light exposure seems to affect, increases. First, I thought it was just circadian rhythm, slow-wave sleep, and growth hormone. But then I learned about its association with fatigue. And gut motility. And thyroid function. And development and treatment of Alzheimer’s disease. And autoimmunity. And mood.

And I was learning much of this over the past week, I have been experimenting with light therapy glasses, combined with an LED stadium light. And I feel like my life has changed profoundly in the past 5 days since adding the light therapy glasses to my self-experimentation.

Today is day 5 of using the light therapy glasses. I’m wearing them now, while I sit in my recliner, at my computer, typing this article. I also have that LED stadium light about 5 feet from my face. And over the past 4 days, for 14 hours per day, I have had the energy of teenager Max.

I hesitate to be so enthusiastic about the positive effects of the protocol I’m using, because in the past, I have occasionally had a few “good” days of high energy and strongly positive mood. On those days, I would wonder what made me feel so great: was it the supplements? Did I change my diet? Was it my recent exercise? Was it the coffee? But this time, I did not change any of those things; I only added the light therapy glasses, and insisted on taking this LED stadium light with me around the house to simulate a 16 hour daytime (like summer months in the northern hemisphere).

And I’ve felt awesome.

I’ve been waking up naturally, without an alarm, at about 6:50 AM. I get out of bed around 7:10 AM, and put on the blue light therapy glasses around 7:15 AM. As I write this (7:45 AM), I feel caffeinated, but I haven’t had any caffeine (only a little water), nor have I had any for months. I’m happy, motivated, and engaged in work, enjoying myself, listening to music, and working. All day long, until 10 PM. So long as I keep my eyes exposed to the LED stadium light throughout the day (exposed to 5,000+ lux) I retain this high energy and elevated mood. Take it away, and I quickly get tired.

That’s another thing that seems to have been affected for me: how long it takes me to go to sleep. Bright light exposure makes a profound difference in my energy level. When it’s near sleep time (10:30 PM) I can be tired and fall asleep within 15 minutes of stopping bright light exposure. During the afternoon, if I stop being exposed to the LED stadium light for about 1 hour, I feel like I want to sleep, regardless of whether it’s 11 AM  or 2 PM or 5 PM. And during this deep dive in the scientific literature, I learned why: bright light enhances cortisol secretion and represses melatonin secretion. Cortisol increases energy and alertness, and melatonin induces sleepiness. Bright light makes one feel awake and alert in two ways: by inhibiting melatonin secretion, and enhancing cortisol secretion. Take away the bright light, and cortisol falls, melatonin rises, and these signal that it’s sleep time. As I learn more about the physiology of bright light exposure, I can’t help but think that most people live in “sleep time” light conditions for most of their lives, and the body functions accordingly (that is, sluggishly and relatively poorly).

Cortisol peaks at awakening time in the morning. One study I quote in the Working Paper is that the morning cortisol peak can be doubled with bright light exposure shortly after awakening. This seems to make an enormous positive difference on energy and mood, and possibly cognitive function.

During my deep dive in the science literature, the link to cortisol made me wonder about a possible association with the many auto-immune conditions that people suffer from, as well as the age-related increase in autoimmune conditions. Cortisol inhibits inflammation and dampens the immune system. Bright light exposure can as much as double the morning peak in cortisol, from which it glides down throughout the day. I wonder: if the vast majority of people do not have normal, peak levels of cortisol in the morning and throughout the day (from retinal light exposure that is “normal” in the context of our evolution) for almost their whole lives, how much chronic illness might be eliminated if they did? I’m thinking about seemingly auto-immune conditions like eczema, psoriasis, Crohn’s disease, irritable bowel, multiple sclerosis, chronic fatigue syndrome, fibromyalgia, hypothyroidism (Hashimoto’s thyroiditis), etc. If the immune system was dampened a bit, would the immune system not attack these parts of the body? Some of them are even treated with prednisone (a cortisol analog). I’m even partly wondering if my seasonal allergies will not happen this year (I expect them to intensity over the next month). I grew up mostly indoors, not getting the normal, natural boost of cortisol that bright light exposure induces; maybe that’s why my immune system is sensitive to things I wish it weren’t? Forever the optimist I am.

And then there are mood disorders. Have you heard of “sundowning” in Alzheimer’s disease? I discuss it in the Working Paper. It’s basically a remarkable increase in confusion, agitation, and aggression at or around the time the sun goes down in people with Alzheimer’s disease. This sounded to me like it was related to the circadian rhythm. It turns out it can be dramatically improved with bright light exposure during the day, or melatonin supplementation at night (and bright light exposure during the day increases melatonin expression at night).

And I haven’t talked about productivity. If the protocol I’m using affects most people in the way it has affected me, what would it do to societal productivity? Or how nice (or mean) people are to one another? Oh, or sleep quality! Bright light exposure enhances melatonin secretion at night, such that in one study, it made elderly people secrete as much melatonin as young controls. That was a remarkable study…

I see so many connections to human health, I have to be careful not to write a book with this Working Paper. But maybe a book at some point is justified…

It’s still early in my self-experiment, so I’m hesitant to recommend it to you, Dear Reader. If I can go two weeks at this level of energy, productivity, and elevated mood, I’ll be more convinced it’s not a confounding variable that I haven’t accounted for, and that chronic bright light exposure is the cause.

Maximus Peto

Max Peto is a longevity researcher and founder of Long Life Labs. A biochemist by training, he studies the biochemistry of aging and longevity and has worked with research organizations such as SENS Research Foundation, Methuselah Foundation, BioAge Labs, Life Extension Foundation, and Ichor Therapeutics. His work at Long Life Labs is focused on empowering people to understand and manage the most critical factors for better health and longer life.

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