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(and why I still use it)

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F.lux, Night Shift, and other screen “filter” apps are not the solution to circadian disruption and poor sleep. Read on to learn why.

Light-emitting Devices

It seems that every week there are new studies and news articles about the dangers of using electronic devices at nighttime. Unfortunately the screens we’re staring directly into emit large amounts of blue light. It turns out that light at the blue end of the spectrum is how our bodies track what time of day it is. Shining blue-enriched light into our retinas at nighttime is screwing with this primordial timekeeping mechanism. And it’s not just making it harder for us to fall asleep. Circadian dis-regulation and chronic melatonin depletion have very serious health consequences that are compounded by lack of quality sleep.

You’ve probably heard the standard advice to stop using light-emitting devices an hour before bed and/or install a program called f.lux on your desktop. For your mobile devices, Android users can install Twilight but iPhone users are out of luck at this point.

F.lux and other screen “filter” apps

F.lux is a free app that automatically shifts the color of your screen to a reddish amber color as the sun goes down. You set it to your time zone and the degree of color shift that you want and it does the rest. The idea is to match the color of your screen to the color of the ambient lighting. In the daytime your screen is in full color spectrum and, as the evening wears on, the color gradually shifts over the course of an hour. Once you get used to the colors, most people love the app and won’t go without it. Of course people doing design work or other color sensitive work may not be able to use it. It can also take some getting use to. Most people start with a mild color setting at first and then gradually turn it further to the red as they become accustomed to it.

The newer version of the app can even sync with the Phillips Hue lighting system and color shift the lights in your home as well! I have not tried this feature yet but it seems pretty awesome.

So what’s the problem?

Not as effective as an actual filter

I have been using f.lux for about five years. The color change didn’t bother me at all and I took to it right away. Four years later, I began to really study the research on blue light and began self-experimenting. I bought a pair of the silly-looking orange Uvex glasses and began putting them on at night. I noticed a huge difference in my sleep onset time and quality. When wearing the orange glasses I got tired earlier and fell asleep faster than any other time in my life. That’s not to say the f.lux is not beneficial. It certainly will reduce your blue light exposure and stress on your eyeballs, but there is a huge difference between minimization of blue light and elimination of blue light. In fact, this study demonstrates that “less than 1 lux of monochromatic light elicited a significant suppression of nocturnal melatonin”! My advice is to go the extra step and block all blue light exposure as part of your evening routine.

High-energy blue light may be damaging your eyes

There is growing evidence that the higher energy blue light light emitted from our devices is damaging to the retinal cells of the eye. Due to the LED backlight, simply shifting the color temperature does little to help this. It is recommended that you use a UV filter or glasses to shield your eyes from these potentially damaging rays. So if you still need to use a filter or wear glasses to protect your eyes, you might as well wear the orange ones to protect your circadian system also! Side note: Most of the products that claim to protect your eyes from blue light but are clear or light yellow, do not filter out the circadian rhythm suppressing wavelengths only the higher energy blue and UV waves.

People tend to hold phones closer to their eyes

One thing that I have noticed with mobile devices running Twilight is that people tend to hold the device closer to their face. The Android Twilight app dims the screen backlight automatically in addition to shifting the color temperature. This is purely my own observations so it may not hold true over the average population. If someone is holding the screen closer to their eyes then they are negating much of the benefits of using the app, as proximity to the light source seems to make a difference in the biological response to blue light.

The “easy button” & the bigger problem

Edison Base LEDPeople are always looking of an easy “set it and forget it” solution. The problem we are facing with blue light exposure is far greater than electronic screens. We tend to read an article that says “blue light at night = bad” then we can “just get f.lux” and go on with our lives. The problem is much greater than just our electronic devices. All energy efficient lighting, LED and florescent, emits strong blue light. Even the “soft white” color lamps have a sharp spike at the blue end of the spectrum. These sources are becoming cheaper and more ubiquitous in our homes and, in some jurisdictions, government agencies are requiring them to be used. Street lights are rapidly being replaced with LEDs with detrimental effects on natural ecosystems. Night lights are usually white LEDs that emit blue light all night long. We need to start structuring our nighttime environments using our knowledge of blue light’s effect on our physiology. Greater public awareness is needed and I hope these apps are a step in the right direction. My concern is that f.lux type apps are acting as a broom with which to sweep the problem under the bed and out of our sleep deprived minds. By wearing high quality orange glasses, you are protecting yourself from all sources of blue light. Not just your computer screen.

Electronic Screens

White LEDAt this point there are two main type of screens on our electronic devices: LCD and OLED. Most screens out there are some sort of LCD except for Samsung phones which use a variation of an OLED (AMOLED). LCD screens are backlit with either a white florescent source or a white LED source. Most computer screens are edge lit with a cold-cathode florescent tube on the top or bottom of the screen and a white diffusion panel that scatters the light uniformly across the screen.

Light Leakage

The main thing to realize about LCDs is that there is always some degree of white light passing through, no matter what color is displayed on the screen. Theoretically OLED screens should have less of a problem with white light leakage as the pixels are self-illuminating (no backlight) and apps like f.lux should be far more effective. I have seen spectrograph of iPhones (LCD) compared to Samsung phones (AMOLED) and they are very similar, however they are always measured with the screen displaying white. I would be curious to see spectrograph comparisons with the screens displaying all black. Unfortunately I do not have equipment sensitive enough to measure light spectrum from screens and have not come across anyone else measuring this.

One of the most effective things that you can do to reduce blue light exposure from screens is to simply lower the brightness. This dims the white LED back light. F.lux will further reduce your blue light exposure but, it is also very important to dim your screen.

Try this at home

You can see for your self the blue light that is emitted from your screen by doing the following test. If you go you BlueLightAtNight.com/black you will see a black page. Take your computer into a dark room and you can see just how much blue light is coming out. Play with the brightness levels. The light that you are seeing is from the white florescent or LED back light. If you put a spectrometer on this it will show the typical strong blue light spike of standard white florescents or LEDs. No matter what color your screen is showing, this back light is always shinning through, you just may not notice it. This is effect is much more prominent on LCD screens that LED.

So why do I use it (and recommend it)?

Despite the fact that I wear orange glasses at night and just spent the last 10 minutes of your time somewhat bashing f.lux, I still use it and recommend it. For one, it is absolutely better than nothing and I think it does help bring awareness to the problem. It certainly relieves eye strain from computing at night. I really like how it transitions in to nighttime mode as the sun goes down. It helps to keep me connected with nature in some small way even if I’m full absorbed into some computer project. I think that any reduction in blue light exposure is beneficial and highly recommended. If you are interested in optimizing your health, I highly recommend you experiment with more effective strategies.

Oh, and did I mention that the f.lux is free! Not only is it free, but the developers graciously provide tech support as well. It seem to me that they are nice people who are very dedicated to helping others and that’s something that I think we can all appreciate.