Before we get to the nitty-gritty science of TrueDark eyewear, it’s helpful to understand the history of light first. During primitive times, humans solely relied on the sun and fire for illumination. Sunlight in particular played a huge role in regulating humans’ natural sleep/wake cycles. Hunter-gatherer tribes would wake up just before dawn (as the sun ascended and the temperature began to rise), and they would go to sleep around 8 or 9pm (once the sun descended and the temperature dropped again). They would also reference the position of the sun to dictate when they should go out and hunt for food.
There have since been many innovations in lighting technology and how light is applied in our everyday lives, such as incandescent light bulbs, fluorescents, and the LED revolution. (Check out this awesome visual for more on the history of lighting!)
Today, we live in an on-the-go society that is always “on”. In other words, humans no longer solely rely on sunlight and fire. We have light bulbs that illuminate our homes, office buildings, gyms, malls, and airports. And thanks to digital devices with LED screens (tablets, smartphones, laptops, etc.), we now have the power of light literally at our fingertips. The lights are everywhere, and they are always on.
Note that sunlight is comprised of red, orange, yellow, green, blue and violet light rays (the visible light spectrum). It’s specifically the blue rays that suppress melatonin levels and promote alertness; blue light is responsible for signaling to your brain that it’s time to wake up in the morning or go to sleep at night time. The key difference and problem that arises from using artificial light sources is that they mostly emit blue instead of the full visible light spectrum.
Many doctors and researchers are concerned about the amount of time people spend using digital devices, and the proximity of these screens to the user’s face, as these variables could have possible long-term effects on eye health, such as macular degeneration (the leading cause of blindness). At the very least, prolonged exposure to artificial blue light, or “junk light” as we like to call it, can cause:
– Inability to focus
Remember that the sun changes its position in the sky and emits different amounts of blue light throughout a cyclical 24-hour period. In order to keep your natural circadian rhythm aligned with the rise and fall of the sun, your body needs different amounts of blue light to promote either wakefulness or sleepiness. That is why TrueDark provides an authentic 24-hour solution to help you block out the right amount of junk light at the right time of day (or night).
In this graph, the red line symbolizes cortisol, which promotes alertness. The blue line symbolizes melatonin, which promotes sleepiness. This pattern repeats every 24 hours.
TrueDark Daylights are available with clear or yellow lenses. Yellow-lensed blue light blocking glasses are truly the most functional for daytime use since they offer the most protection against junk light without making you too tired during the day (like orange or red lenses would). Traditional yellow lenses usually block up to 70% of blue light; TrueDark’s yellow lenses actually block 75% of 380nm-500nm light wavelengths thanks to their polarization.
Please note: blocking more than 75% of blue light during the day can actually have adverse effects, like making you feel more sleepy when you need to be active and alert. This is the key reasons why orange and red lenses are not appropriate for daytime use.
Our clear daytime lenses comparatively block 34-40% of 380nm-500nm light wavelengths, which is significantly less than the yellow lenses, but significantly more than blocking 0%! These lenses simply offer a stylish, yet practical alternative for people who:
– Don’t want to wear yellow lenses out in public
– Need to see true colors on a computer screen (e.g. graphic designers)
– Need to stay in uniform at work (e.g. flight attendants)
Please note: clear lenses can NOT block any more than 40% of blue light without the lenses turning more yellowish in color. Similarly, 75% is the most amount of blue light that yellow lenses can block before they turn more orange.
TrueDark Twilights specifically have red lenses to block out blue, green and violet wavelengths of light at night. Science has shown that these specific wavelengths can suppress the body’s ability to suppress melatonin production at night time. When your body doesn’t produce melatonin, you have a harder time falling and staying asleep. When you don’t sleep, you put yourself at greater risk for a number of short and long-term health conditions, including but not limited to:
Sleep deprivation can also notably affect your cognitive function and ability to perform your best. If you’re not getting adequate sleep, you have less control over your emotions, and you’re more likely to make poor decisions.
Twilight Classics are our strongest pair of sleep-hacking glasses, as they have a full wrap-around style to block 100% of 380nm-580nm blue, green and violet light wavelengths.
Twilight Elites and Sleep-Hacking Fitovers use the same science-backed technology as the Twilight Classics. The key difference is that they block 98% of 380nm-580nm blue, green and violet light wavelengths instead of 100%. They block slightly less as the lenses are engineered to allow a little more visibility at night enabling the wearer safer mobility around the house during the evening hours. When choosing a pair of our sleep glasses, it really comes down to which style you prefer. Twilight Fitovers are notably ideal for people who already wear prescription glasses or readers.
Twilight Sunsets have patent-pending red-to-amber gradient lenses that are darker on the top and lighter on the bottom. This style is best suited for those that tend to work later into the evening, but that still want to be able to fall asleep relatively quickly. Since these are lighter on the bottom, you can still see, read, and write, but your mind will have an easier time relaxing into an alpha (or meditative) state when it’s time to go to bed.
To get a better sense of how lens color affects the amount of junk light blocked, and how TrueDark’s eyewear lines up, check out the chart below: