What Is Blue Light?
Blue light is a perfectly normal and natural spectrum of light that is found in sunlight.
Light ranges from 400 to 700 billionths of a meter (nanometer, nm) 400nm being violet to 700nm being red. When combined the individual spectrums of light creates “white light” or sunlight.
Sunlight consists of a range of coloured light including red, orange, yellow, green, blue, indigo and violet – when we see a rainbow we are seeing the light rays from the sun refracted through rain drops and splitting the light spectrums, similar to seeing light through a prism.
The useful range for colour vision in humans is approximately 450 to 650 nm. Visible blue light has a wavelength between 400−525 nm,
High-energy visible light is high-frequency, high-energy light in the violet-blue band of the visible spectrum from 400 to 450 nm. High-energy visible light is found in sunlight as well as in artificial light sources such as fluorescent and light-emitting diode lighting, smartphones, tablets, laptops, televisions, and many other electronic devices.
Is Blue Light Safe?
Blue lights has its benefits and draw back, it will depend on how much exposure to blue light you have over how long a time – we are talking years here.
Humans and animals have been exposed to blue light since the dawn of time, we have all felt the positive benefits of the sun on our mood or state of mind, however in more recent years the levels of our exposure to blue light has risen due to the introduction of LED’s (Light emitting diodes) and our increasing use of devises such as laptops, mobile phones and e-readers
The Canadian Association of Optometrists (OPTO) state “Evidence suggests that exposure to blue light in the 470 – 490nm wavelength range (lower energy) is less damaging to the eye than blue light in the 400 – 470nm wavelength range (higher energy) and essential for maintaining a healthy circadian rhythm. Development of LEDs with a peak emission in the safer range may represent an important advancement for ocular health.
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) provided guideline levels of blue light exposure where they considered health risks to be unlikely.
Range of Digital Device Blue Light Exposure Type of Device
| Type of Device | % of ICNIRP Limit |
| Desktop | 0.71 – 1.26 |
| Laptop | 0.63 – 1.97 |
| Tablet | 0.43 – 2.38 |
| Smartphone | 1.78 – 4.09 |
Thus, clinicians may conclude that the magnitude of exposure from digital devices does not approach dangerous levels.
When speaking for opticianonline Dr Shelby Temple senior research associate at Bristol University said “To be exposed to that same amount of dangerous high energy protons during a 20 minute walk or drive to work, you would need to spend 133 hours looking at your phone or computer screen continuously.”
Blue Light And Sleep
Humans and animals alike rely on light from the sun to tell us when to wake up and when to go to sleep, by interrupting the natural amount of light the body receives will alter our sleep pattern.
It’s not just LEDs that can effect sleep patterns, for many years healthcare professionals have been aware that people exposed to too little light can find their health compromised. Night shift workers can suffer from increased sugar level, raised blood pressure, heart disease and obesity.
Our natural Circadian rhythm is altered by the amount of artificial light all around us, our circadian rhythm effects our sleep-wake cycle, during daylight our body clock sends signals to the brain to keep us awake and alert, as the light falls at dusk our body clock initiates production of the hormone melatonin to prepare us for and then keep us asleep.
