How To Use Light To Optimize Your Mind

Improve your sleep, increase focus, raise testosterone, & lower inflammation using the power of light

Keenan Eriksson
Mar 12, 2019 · 20 min read

Light has a pretty profound influence on our biology. Light exposure affects our sleep, our hormones, exercise recovery, and even our ability to focus.

In fact, junk light may be a major influence in the manifestation of ADHD and other focus problems.

In this article, I will show you exactly how you can make changes in your life to optimize your light exposure — which will improve your sleep, enhance exercise recovery, improve your hormones, and increase your focus.

I’ve been biohacking (using science and biology to improve my performance) for close to 5 years, and optimizing your light habits is one of the easiest, most common, and most effective methods I know for improving mind function.

It doesn’t take much work to get improvements, either, thankfully. Good light habits mostly involve using some simple tools or making slight tweaks to the ways you already do things.

If you’re skeptical, I don’t blame you, so first I’ll address the science behind this in the next section. From there we will get right into changing your light exposure, and even show you some ways light can be used as a direct therapy.

The Science

There are a few ways light influences our biology, but one of the most prominent impacts on modern humans is the effect of artificial blue light. I don’t mean light that literally looks blue (though that is blue light as well), but rather light that oscillates at a high frequency.

Think of it this way: for most of human history, the only sources of light were the sun and fire.

Though it often appears white or yellow to us, the sun emits multiple colors of light, including red, orange, green, and blue, as well as the invisible infrared and ultraviolet light spectrums.

As you move across the spectrum of visible light, the wavelength of the light decreases and the energy increases. Red light has the longest wavelength and has the lowest energy of the visible light, while blue and purple have the shortest wavelengths and the highest energy.

This zone of blue and purple light is known as HEV light, which stands for High Energy Visible light. For simplicity, HEV light is often referred to simply as “blue light.”

As the sun moves through the sky, there is less or more blue light depending on the time of day. At the beginning of the day, there is less blue light outside, and it increases throughout the day until the sun is at its highest point in the sky, then declines again until the sun goes down.

This is the light pattern our evolutionary biology was influenced by for most of human existence. The mastery of fire didn’t change this much, since flame emits fairly low-energy light.

But our light exposure changed radically with the invention of artificial light, and especially in the past 50 years, with the invention of fluorescent light bulbs and LED lights.

Nowadays, our environments remain well-lit long after the sun goes down, and the lighting we use emits high amounts of blue light—similar to the sun at the brightest part of the day. Our bodies are not used to it.

An analysis of 85 studies performed regarding the effect of Artificial Light at Night (ALAN) revealed that ALAN can increase the risk of breast cancer, disrupt circadian rhythms by negatively affecting melatonin production (it prevents you from being able to sleep), and may have negative consequences for mental, cardiovascular, and metabolic functions (bad for your brain, your heart, and for weight loss).

Furthermore, new Light Emitting Diode (LED) lights may have particular consequences that transcend those of fluorescent lights. LED lights emit high-intensity blue light that is absent in the daylight spectrum—that is, it’s brighter than the blue light emitted by the sun.

LED lights damage the retina of our eye, contributing to vision problems and blindness. The American Medical Association has even released an official statement of concern regarding the harmful potential of LED lighting.

There is also a phenomenon known as Irlen Syndrome, a condition where the brain has a more difficult time processing high-energy blue light, which causes mental fatigue and manifests in learning problems. Using color lenses or overlays—known as the “Irlen Method”—improves reading rates for a significant percentage of children (especially those with dyslexia). The prevalence of Irlen Syndrome may be much higher than realized, because so few people test for it, and it may contribute to trouble focusing or reading for extended periods of time.

Mastering Light For Your Benefit

Now that we know a few things about how light affects our biology, we can use light to improve ourselves. Not only can too much of the wrong light at the wrong times be bad for your health and focus, but getting the right light at the right times can enhance them.

In this section, you’ll learn to optimize your light habits — not only by lowering your exposure to artificial light but also by learning to use light as a therapeutic tool.


Sleep is one main area where light exposure habits affect our health.

Better sleep is also one of the most powerful ways to improve your mind. Remember: Sleep is the only time your brain repairs itself.

Using a system known as the glymphatic system, your brain clears out cellular garbage and literally cleans itself. But this only happens when you’re asleep.

There are a ton of other beneficial processes that occur, but for now, just understand that the better you protect your sleep, the better your brain will function.

As we’ve already mentioned, artificial light at night hinders your body’s ability to produce melatonin, which is the essential hormone involved with inducing your sleep cycle. Therefore, you can optimize your sleep by lowering your exposure to artificial light after sunset.

Ideally, you would stop using all artificial lighting when the sun goes below the horizon, but for most of us, this isn’t realistic. However, you can make efforts to lower the amount of blue light you get exposed to without having to go pitch dark.

Device software

Screens are one of the main sources of artificial light in our lives, but you can lower it using simple software.

f.lux is a free program available for most computers that lowers blue light by changing the screen to a more amber color.

F.lux is great, but it is also simple.

If you want to get even more benefit, I strongly recommend Iristech. Iristech isn’t free like f.lux, but it is much more extensive and works with your computer’s video card to make your screen as harmless as possible.

Not only does it adjust the light from your screen as the day progresses, but it also reduces screen flicker and optimizes other factors that make screens a disruptive element when it comes to light.

If you can’t find a screen software that works with your device, there are a few other hacks. Remember, red light is the lowest energy light of the visible spectrum, so technically, red light is the best color you can use when trying to avoid blue light.

Well, if you’re an iPhone user, you can actually set your phone to use red light for the screen, and easily switch into this mode when you want to.

To do this, first go to:

Settings → General Settings → Accessibility.

Scroll all the way down and select “accessibility shortcut,” and select “choose color filters.” This sets your home button to triple-click to turn on your color filters any time.

Now you need to set those color filters up for red light. Go back to Accessibility:

Accessibility → Display Accommodations→ Color Filters

Select “Color Tint,” and scroll all the way to the bottom to set the sliders below that intensity and hue are both all the way to the right in order to remove all blue light from your phone screen.

Now press the home button 3 times to turn it off. And try turning it on again by another three presses. Voila! Instant escape from blue light whenever you want.

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Setting the IOS option for the home “triple click” setting on the left. On the right, setting up the color filters to turn the screen red when they are enabled.

During the day, I use the Iris software on my laptop. The Iris software has a drop-down menu of pre-set screen settings, or you can choose to customize the software yourself.

I like to stick with their pre-sets, and I keep my screen set to the “health” pre-set during the day, then at 6:30pm I’ll open the Iris program and manually switch to the “sleep” pre-set, which eliminates all blue light from my screen.

Blue light blocking glasses

Blue light blocking glasses might be one of the most popular items in the world of biohacking these days, and for good reason. Basically, instead of having to worry about artificial light all the time, you can just wear special sunglasses that filter out the most disruptive rays.

As you’ll learn, there are multiple levels of investment when it comes to blue-light blocking glasses, from simple gas station shades to glasses that are customized based on your unique light sensitivity.

With that said, something is better than nothing, and if you’re worried about price, a simple pair of orange-tinted safety goggles or gas station glasses works wonders.

For the average person, I personally like gaming glasses, particularly by the company Gunnar. Gunnar glasses are designed to help reduce eye strain for professional video gamers, and they are not only great at blocking blue light but are stylish as well.

You can find Gunnar Glasses both on Amazon as well as on their website, where you can customize them as necessary

If you have Irlen syndrome, then you can actually boost your focus by using blue light blocking glasses during the day, and not just at night. The next level above Gunnar glasses would be to get yourself a custom pair of Irlen glasses.

Morning blue light

This technique actually involves using blue light rather than avoiding it, though the easiest way to implement it is by using the sun.

Research on circadian rhythms has found that pulses of blue light in the morning can advance the rhythm of melatonin. Basically, exposure to about 30 minutes of blue light in the early morning helps your body produce sleep hormones on time in the evening. This can help combat the effects of blue light at night, which has the opposite effect of delaying your melatonin cycle to later times.

There are some fancy devices out there that can help you get this effect artificially, but the sun is your best tool for this technique. Just going outside for 20 to 30 minutes as the sun is coming up can help set your circadian rhythm for the whole day.

Maybe it’s just psychological, but I feel like days when I start off with an outdoor workout, a walk, or an open-eyed meditation session, I get better sleep the following night than if I’d done the same thing indoors.

Now, I’m usually combining multiple techniques to optimize my sleep, such as the aforementioned light techniques, evening journaling, alternating hot/cold showers, and foam rolling, but when weather permits and I can get outside in the morning, I feel a noticeable difference the next night.

I don’t spend a ton of time recording my sleep, but on the occasions where I’ve gone out of my way, I’ll usually notice a 10% or greater boost in sleep quality.

Here are the scores for my sleep quality after a rainy day with no time spent outside, vs. the sleep from the next night after I spent most of my time out on the patio working on my computer in sunny weather:

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Screenshots by the author.

As you can see, I fell asleep just before 1 am on both days, and woke up just after 8 am. Yet on Thursday night after I’d spent the day outside, my sleep quality was 15% higher.

Other than sunlight exposure, the only major difference between the two days is that I walked 4,000 steps less on the day that I ended up having better sleep. Normally, exercise that isn’t too late in the day aids sleep quality, so this figure should have made my night worse (if anything).

If you want to get really technical and guarantee access to morning blue light no matter what the weather, you can invest in special biohacking gear that will prime your circadian rhythm for you.

One such device, known as the re-timer, shines pulses of blue-green light frequencies around your eyes for 60 minutes to help reset your sleep patterns. A session with the re-timer first thing in the morning will help you go to sleep earlier and wake up earlier the next day. I don’t personally use a device like this, but I live in Texas, so sunlight is plentiful throughout most of the year.

However, if you live in northern states, this and other photobiomodulation devices are a great investment to compensate for the lack of sunlight during the winter months, especially if you suffer from hormone or mood issues, which can result from too little sunlight and Vitamin D.


The last section was about the power of morning sunlight for aiding sleep patterns, but in general, sunlight has several benefits for your biology.

In recent years, Vitamin D has become very popular in the medical community as a supplement. However, supplemental Vitamin D is pretty controversial, and can have consequences if taken improperly.

This is unfortunate because Vitamin D is an essential component in optimal hormone function, and our hormones dictate everything from our mood to our sex drive to muscle recovery after exercise.

Your body makes Vitamin D naturally when exposed to sunlight, and even as little as 20 minutes of exposure to the sun can be enough to get your daily values of Vitamin D.

We already covered one way that sunlight can optimize your hormones: by using morning sunlight to cause earlier melatonin production in the evening.

But sunlight also increases serotonin, which is a neurotransmitter associated with feelings of happiness, and is the main neurotransmitter associated with depression when it is too low.

This is a primary factor of why people get Seasonal Effective Disorder (SAD), or “winter blues,” during the cold part of the year. As the weather gets colder, people go outside less, and the sun simultaneously appears for fewer hours during the day.

This creates a one-two punch where people who live in northern states face both harsher weather conditions that keep them from getting enough sun, as well as fewer hours of opportunity to do so.

If that’s not enough to emphasize how sunlight can be used to improve your life, recent studies have linked sun exposure to increased testosterone production in men, as well as increased libido. Think about it: beach cultures are hubs for the muscular and athletic, and Muscle Beach has been world-famous as an outdoor gym ever since the days when Arnold Schwarzenegger and other major bodybuilders frequented it.

They may not have known the science at the time, but beach communities benefit from a constant testosterone supplement and aphrodisiac just by spending their time outside. Exposure to light has been shown to increase testosterone levels and interest in sex in mean above the age of 40.

Regarding testosterone, sunlight exposure to your private regions may be the most effective method.

A Korean study showed increased testosterone production in male rats whose you-know-whats were exposed to low-level red light lasers, and another study showed increased function and size of sexual organs after weeks of sunlight exposure.

A study on humans published in 1939 is often cited as evidence that sunlight exposure on the genital area increased testosterone in men by 200%, whereas exposure to the chest only resulted in a 120% increase. I haven’t purchased and read that study myself… it’s from 1939, after all. Nonetheless, you have my permission to tan in the nude — just don’t get sunburned down there.

Hopefully, you have high fences.

I haven’t done significant reading on possibly similar effects of sunlight specifically for women. However, it does appear that exposure to sunlight can help reduce osteoporosis, improve Vitamin D levels in specifically at-risk people like nursing mothers, improve fertility in those receiving IVF treatment, and reduce the risk of breast cancer for those with light skin.

Doesn’t excessive sunlight increase your risk for skin cancer? While I don’t believe it’s as severe a risk as people emphasize, I’d be remiss to tell you otherwise. The data does support the idea that sunlight, in excess, raises your risk for some cancers. However, it appears that this risk is greatest when you get sunburned, but is less of a factor when you tan slowly and evenly.

Furthermore, most sunblock and sunscreens may be more carcinogenic than sun exposure. A series of active chemical ingredients common in sunscreen are under scrutiny as being potentially cancer-causing in humans. I’m not going to make a claim; the research is not complete. However, in general, I tend to avoid synthetics and chemicals where possible.

One little interesting tidbit to know is that, despite a lack of direct evidence, skin cancer rates have risen in tandem with sunscreen use. This could mean people are just more careless about sun exposure because of sunscreen (though in that case, I’d question the effectiveness of sunscreen in the first place), but it could mean that sunscreen itself is harmful. Then again, there could also be completely unrelated factors, like poor diets, that increases susceptibility to skin cancer.

Long story short, while I do suggest getting more sun exposure, be careful. I don’t think that the risk of skin cancer from sun exposure is as big as people think, but sunlight is not harmless either. Make sure you aren’t regularly sunburning yourself, and be extra careful if you have a pale complexion.

Melanin is the pigment your body creates that causes a tan, and it is your body’s personal mechanism to protect itself from the sun’s UV light rays. Even with all my belief in the benefits of sunlight, I don’t recommend sun exposure, for example, to my Dad. He is pale and doesn’t tan whatsoever, and low-and-behold, he had skin cancer years ago despite generally avoiding sunlight.

With that said, my best training always seems to occur in the middle of the Texas summer. Despite the intense heat, which reaches 100 degrees Fahrenheit by mid-June and often doesn’t dip below 90 again until October, this has always been when I feel the most active.

Part of that is probably because I used to lifeguard, meaning I’m used to high amounts of sun exposure, and though indoor rock-climbing was my sport at the time, getting sun while on the job helped my performance.

In fact, it has been during the summer that I tried most new athletic activities. I got into rock climbing in the summer, started biking to work during the summer, discovered CrossFit, and even did hot yoga for the first time during the summer (fun fact, the yoga studio had a temperature of 90 degrees Fahrenheit while outside it was over 100. Though it was more humid in the studio, it actually felt cooler than walking outside).

I haven’t done blood testing to see how sunlight effects testosterone in my own body, but I am a believer and can anecdotally say that there has been a connection between higher amounts of sun exposure and more athletic activity in my experience of life.

What I recommend

  • Get at least 20 to 30 minutes of sunlight exposure at least 3 times a week, wearing as little clothing as possible. This will increase Vitamin D, and is enough for many people to hit their daily recommended values without outside supplementation.
  • Make your own decision regarding sunscreen, but if you aren’t going outside long enough to risk a sunburn, I’d recommend not using it. While there isn’t much data to connect sunscreen to skin cancer directly, rates of skin cancer have only risen with the increased use of sunscreen.
  • Avoid sunburn. Build up slowly to spending more time outside, and try to get an even tan over your whole body, rather than allowing farmer’s tans to develop. Your tan is the result of melanin, the body’s personal defense system against UV rays.
  • If you have access to a fenced backyard or a nudist beach, get some sunlight exposure to those areas that rarely see it.
  • If you are very pale in complexion, or cannot get sunlight during winter months due to the climate of your location, consider investing in photobiomodulation gear to replicate these effects artificially.


Use of devices that emit therapeutic light is known as “photobiomodulation” and has become popular enough that it is being looked at as a potential treatment for diseases like Parkinson’s, as well as having been used by Olympic teams to improve recovery during exercise.

We’ve actually mentioned a photobiomodulation device already. The re-timer device mentioned is a form of photobiomodulation: use of artificial light as therapy to benefit our biology

And while blue light can be used therapeutically, it’s red light that shows the real promise. Certain frequencies of red and infrared light can be used therapeutically to provide many of the same benefits of proper sunlight exposure, without the skin cancer risks.

Furthermore, devices that emit these light frequencies are available for year-round use, whereas access to the sun is often limited by weather and time.

In particular, the two common therapeutic forms of infrared light are near-infrared light and far-infrared light.

Near-infrared penetrates the skin at low frequencies. At the high-frequency range, it gets deep into our tissue where it causes a strong release of nitric oxide and stimulates ATP production by the mitochondria. For those of you biology geeks out there, you already know that the mitochondria are the powerhouse of the cell.

What this means is that the mitochondria are our body’s first and foremost energy producers, and anything that boosts the health of our mitochondria will boost our health as well. In fact, dysfunction in the mitochondria is being looked at as a main culprit in the formation of complex, chronic diseases such as Parkinson’s, Alzheimer’s, Chronic Fatigue Syndrome, and Multiple Sclerosis.

The benefits of near-infrared light therapy include:

The best devices for near-infrared therapy, that I know of, are those by the company Joovv. Joovv also runs one of the best websites for learning about light therapy and is an incredible resource for diving deep on this topic.

Joovv devices look like wall panels covered in little red light bulbs. These bulbs emit red and infrared light at frequencies considered to be therapeutic. Joovv devices boast an impressive range of benefits, including most of the ones you get from exposure to sunlight, such as increased testosterone. Joovv primarily operates through skin exposure, but you can also use infrared light therapy to improve the health of your brain.

Another near-infrared device called the vielight operates by blasting light into your brain through your nostril (yep, you read that correctly — it goes in your nose). Vielight and similar technology are currently being studied to treat the symptoms of Alzheimer’s disease.

Near-infrared light is able to induce neuro-regeneration, making it a powerful potential therapy for neurodegenerative conditions like Parkinson’s, Alzheimer's, and many other diseases.

For day to day use, the vielight and similar devices are often nicknamed “a cup of coffee for the brain,” and are associated with increased clean energy that can last throughout the day.

I don’t personally own a Joovv or a Vielight (neither am I affiliated with them in any way). However, the science behind these devices is so promising, and so many people don’t have access to year-round sunlight that I feel I would be remiss not to include these details.

I have come across the Joovv in functional medicine clinics, however, and spending some time in front of it gives me a feeling of relaxation and energy simultaneously. I definitely like the product, and it’s on the wishlist for my own personal biohacking gym.

While I don’t have a Joovv or a vielight, I do take advantage of infrared saunas.

Infrared saunas are a photobiomodulation technology that relies primarily on far-infrared light, which has similar effects as near-infrared. Though far-infrared is not as powerful as near-infrared, these saunas combine it with the benefits of heat-shock therapy for a powerful compounding effect.

Regular dry saunas (not infrared) increase brain-derived neurotrophic factor (BDNF) and human growth hormone as a function of heat-shock proteins which are created by your body in response to, well, the heat. This seems to have a detoxifying effect. When you combine this with the skin penetration from far-infrared light of an infrared sauna, which in turn stimulates the mitochondria, you end up with a powerful cocktail of performance boosting benefits.

Be careful when doing sauna work, as overdoing it can lead to heat injury or heart problems. Make sure to hydrate well, and don’t push yourself to the point of dizziness. A good rule of thumb is to stay in a sauna past the point of discomfort, but leave before you feel dizzy. It’s better to go into a sauna for 10 minutes, then cool off for a while and return, than to do 20 minutes all at once.

That said, infrared saunas tend to operate at lower temperatures than dry saunas, leveraging the benefits of the far-infrared light to give you more benefit with less discomfort. One or two rounds of 15 minutes in an infrared sauna, separated by a 30-minute cool-off session spent outside the sauna, can set you up for the whole day.

When I was training for the CrossFit games in 2017, simple sauna sessions like this helped me feel amazing, relaxed, and happy throughout the whole day. I’d combine sauna work with meditation and visualization drills where I imagined myself feeling happy and achieving my dreams, and sometimes this became downright spiritual.

I cannot overstate the benefit of a healthy sauna practice. For me personally, the best use of the sauna was separate from any gym training, purely as a relaxation technique. I would go to the sauna and sit inside for up to 15 minutes, then take a cold shower and wait 15 minutes, and repeat until I had done 3 rounds in the sauna. The effects were so profound and calming that I’d eventually develop a habit of going to the sauna 4 to 6 times per week.

Finally, you can buy your own far-infrared sauna, but they are expensive, and a good one can cost you $5k or more. The best way to use this technology is to find a local health club that has one. Most cities will have a few available. They have become popular enough that even major gyms are starting to implement the technology to replace their dry saunas.

If you are hell-bent on owning one yourself, I recommend the brand “clearlight” for their quality control and effectiveness. Just search “clearlight sauna” and you’ll be able to find retailers quickly.

In Conclusion

Light is an intricate and inescapable reality in our lives, and it does a lot more than it let us see.

We evolved over countless millennia to respond to specific light patterns throughout the day, and by replicating these light patterns, we can increase our performance and improve our health.

The techniques necessary to optimize your light habits are simple, and you can make improvements simply by downloading some software on your devices and getting a pair of orange sunglasses.

For those who really want to dive deep, special devices can be used to increase recovery during exercise and improve brain function. This field, known as photobiomodulation, involves shining specific therapeutic wavelengths of light on your body for a biological benefit. Examples of such technology include near-infrared, far-infrared, and blue light therapy devices.

Personally, optimizing my light habits is one of the easiest and most efficient changes I’ve made to improve my performance in the last year, with benefits for sleep, recovery, testosterone, mood, and skin health.

Furthermore, most of the techniques I use are freely available, such as simply getting more sunlight or turning off artificial lighting at night.

Better Humans

Better Humans is a collection of the world's most…

Thanks to Terrie Schweitzer

Keenan Eriksson

Written by

Founder: ISSA Certified Trainer, Ziglar Legacy Certified Speaker, Biohacker, Perspectivist, Conscious Carnivore

Better Humans

Better Humans is a collection of the world's most trustworthy writing on human potential and self improvement by coaches, academics, and aggressive self-experimenters. Articles are based on deep personal experience, science, and research. No fluff, book reports, or listicles.

Keenan Eriksson

Written by

Founder: ISSA Certified Trainer, Ziglar Legacy Certified Speaker, Biohacker, Perspectivist, Conscious Carnivore

Better Humans

Better Humans is a collection of the world's most trustworthy writing on human potential and self improvement by coaches, academics, and aggressive self-experimenters. Articles are based on deep personal experience, science, and research. No fluff, book reports, or listicles.

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