short-wave optical radiation
(blue-light)
Components of Visible Light - Conceptual Dispersion
Source: LucasVB (Light dispersion conceptual waves.gif)
Via Wikimedia Commons [Public domain]
Short-wavelength optical radiation or simply "blue-light" plays an important role in the regulation of our circadian rhythm, because it suppresses the production of melatonin, the hormone secreted in the pineal gland that regulates our sleep-wake-cycle. (See these studies for reference: 1, 2, 3)
Being exposed to blue-light during the day is perfectly fine and even important (blue-light is a natural part of the Sun's light spectrum). However, regularly suppressed melatonin at night has been shown to possibly lead to type-2-diabetes, metabolic syndrome, obesity, heart disease, impaired immune system function and finally increased risk of cancer (4, 5, 6, 7).
...Of course suppressed melatonin also directly influences sleep quality in a negative way and causes sleeplessness, or insomnia (8, 9). This in itself is a burden to your overall health and well-being resulting in cognitive function impairments (e.g. attention, concentration and memory deficits), emotional dysfunctions (e.g. mood swings, or depression) and generally increased biological as well as psychological stress levels.
Why am I telling you this? ...Well, because short-wavelength optical radiation is emitted in high doses by cellphones (among other devices like tablets, computer screens, televisions and even artificial lighting). Self-luminous electronic displays must emit blue-light to produce white light. The emitted spectrum unfortunately fully covers the wavelengths of peak sensitivity for our circadian rhythm and melatonin secretion - between 446 - 477 nm (10).
Linear Spectrum of Visible Light - Wavelengths in Nano-Meters (nm)
Source: Gringer (Own work), via Wikimedia Commons [Public domain]
Our cellphones are therefore a major cause of melatonin suppression at night, thereby reducing sleep quality, disrupting our circadian rhythm and in the long run causing the adverse health effects described above (11).
You can subjectively assess for yourself that the effects of sleeplessness, insomnia, or decreased sleep quality can be directly associated with artificial light exposure and the use of electronics at night by doing some simple experimentation at home.
If you have been experiencing problems falling asleep without knowing why, you might just have found the reason.
Given the serious consequences that melatonin suppression has on our health and considering that all our self-luminous electronic displays emit this melatonin suppressing blue-light at critical levels, preventing exposure at night should be a primary concern for all of us - keep this in mind, especially if you have children!
Going off-grid after sunset is not a realistic option in today's electrified and illuminated world. Nevertheless, this would obviously be the best choice for your sleep quality and overall health, because even your regular artificial room light most likely contains melatonin suppressing blue-light (12). Fortunately there are effective and more applicable ways to improve the issue other than completely switching off.
Concerning indoor lighting at night, Compact Fluorescent Lamps (CFLs), High Intensity Discharge lamps (HID), halogen lamps, neon lamps and Light Emitting Diodes (LEDs) should be avoided, if possible.
RULE OF THUMB:
The "warmer" the light appears (shift towards the red part of the light spectrum) the better - meaning less blue-light.
A great option for the bedroom are salt crystal lamps. The spectrum that these lamps emit contains no blue and UV light. Moreover, these lamps are said to have other great health benefits as well.
Personally I consider the best overall solution to be wearing special amber lensed, blue-light blocking goggles at home after sunset (13, 14).
These are often sold as "computer glasses" and you can get them online, from your local optician, or even from a regular hardware store. Research online before you make a purchase. Prices between the different available models and manufacturers vary greatly and the most expensive ones do not necessarily deliver the best results.
Normal sunglasses also block a decent amount of blue light, since they are designed to filter UV light, which comprises the next shorter wavelength range in the electromagnetic spectrum - however, they are obviously dark.
Now to our self-luminous electronic displays:
It is quite easy to block a high amount of the short-wavelength optical radiation from cellphones, tablets, computer displays and TVs without notably distorting display quality, transparency, or brightness.
This can be done by placing special blue-light filtering synthetic-, or tempered glass sheets over the screen.
...This approach is implemented in our blue-light blocking screen protectors. Additional benefits of these very thin, self-sticking PET films are that they protect the display from breaking, scratches and fingerprints and they repel oil and other liquids.
Check out the products and product descriptions here, or under the products tab of the head menu, if you haven't done so yet.
*Note: We only sell these blue-light filtering screen protectors for iPhones. For Android smartphones/tablets, jailbroken iOS devices and computers there are software solutions available free of charge...
Apple is currently working on a software feature called "Night Shift", which will be similar to the apps described below. As soon as the feature is released we will stop selling these screen protectors as we believe that a software solution is much more effective and environmentally friendly.
A great tool to solve the blue-light-at-night problem on your computer is a free program called "f.lux". If you install the software and set your timezone, it will automatically adjust the color of your computer's display to the time of the day, incrementally cutting out blue-light in the evening and at night and modeling sunlight during daytime. Simply go to www.justgetflux.com and download it from their official website.
**Note: f.lux is available for jailbroken iOS devices through Cydia.
For Android users there are free and paid apps available in the Google Play Store that work just as well. I have made good experiences with the Twilight App, but there are others as well.