With constant technological advancement in horticultural light systems, indoor

growers who choose LED lights may be able to calculate higher yields for their

plants in shorter amounts of time. But scientific breakthroughs benefitting

the growth of your plants might pose unseeable risks to your eye health,

especially long term.
Most grow lights on the market are manufactured for specific wavelengths

targeting different stages of plant growth: red Light Emitting Diodes (LEDs)

activate seed, root, flower and fruit production; blue LEDs make strong stems

and roots; and both have a strong role in active photosynthesis. On the other

hand, plants also need yellow light, like that produced by High Pressure

Sodium (HPS) fixtures, for photorespiration, or the growth stage where plants

consume most of their nutrients. Though many growers use HPS and other

combinations of light sources successfully, new full-spectrum LEDs are

becoming more available as an energy-efficient and economical choice for

high-yield grows.

Full-spectrum LEDs and UV radiation
Why should growers consider full-spectrum LEDs? LEDs utilizing the full light

spectrum replicate the effects of natural sunlight more closely than other

artificial light sources. When the entire light spectrum is available to

plants, they can differentiate between each targeted light spectrums, which we

see as colors, for higher absorption and cellular activation. The full

spectrum that includes rays both visible and invisible to the human eye appear

white in color when active simultaneously. Though the white, sun-like

conditions make it easier to see normal colors with the naked eye (as opposed

to traditional LEDs that appear pink or purple, or HPS lights that appear

yellow), the highest risks of eye and skin damage exist in the invisible UV

rays emitted by these lights. Later, we’ll mention the potential risk of

visible blue light that’s also present in these types of fixtures.

Any artificial light used for indoor growing emits a certain amount of UV-A

and UV-B Radiation by default, since these rays are what contribute to

photosynthesis in natural sunlight. Almost anyone who’s ever worn sunblock is

familiar with UV-A and UV-B, the most well-known types of UV radiation emitted

by the sun. A third type of UV Radiation, UV-C, is also present in natural

light but is almost 100 per cent absorbed by the Earth’s atmosphere. With

artificial light, particularly full-spectrum LEDs, there is a high probability

of UV-A and UV-B Radiation, but also potential exposure to UV-C Radiation,

which poses the most serious risks to eye and skin health.

UV light and cataract formation
According to the Journal of Environmental Health Perspectives, “Ultraviolet

light exposure to the eye has been associated with cataract formation and

retinal degeneration. In both cases, it is hypothesized that ultraviolet light

can initiate formation of free radicals, which can cause protein modification

and lipid peroxidation.” In short, the UV Radiation emitted by full-spectrum

LEDs may pose a higher risk to eye health than other types of artificial

light, and those exposed should always protect their eyes from these harmful

rays.

High-energy visible light — blue light
We’ve touched on the risks of exposure to UV light and explained why

utilizing the full-spectrum of light may be beneficial for plant growth. But

between lower-energy visible light and high-energy UV light, there is blue

light, also known as High-Energy Visible (HEV) light. There’s a lot of

information circulating about HEV light due to increased use of computers,

cell phones, and other devices emitting blue light. Full-spectrum LEDs are

certainly one of these devices.

Though the risks of eye exposure to HEV light may not be as damaging as UV

light, it can have adverse affects on your overall health. While UV light can

damage the cells of the eye and lead to degenerative eye diseases over time,

HEV light affects hormone balance and fatigue, particularly due to its effect

on melatonin levels, which regulate alertness and sleep cycles. From the

Harvard Health Letter, 2012: “While light of any kind can suppress the

secretion of melatonin, blue light...does so more powerfully. Harvard

researchers and their colleagues conducted an experiment comparing the effects

of 6.5 hours of exposure to blue light to exposure to green light of

comparable brightness. The blue light suppressed melatonin for about twice as

long as the green light.” This imbalance may be why those who spend extended

periods of time exposed to artificial light, such as indoor horticulturists,

experience unwanted fatigue, headaches, eye pain, or trouble sleeping.

LEDs have always been an efficient choice, producing less heat and taking up

less space than other light sources. Though they may pose a higher initial

investment, they tend to last longer and have a lower environmental impact

than HPS or Ceramic Metal Halide lights, though these lights are still widely

used with great success in indoor grows. No matter what light source growers

ultimately choose, these technologically advanced devices can pose risks.

Knowing the risks can help you make an informed decision about protecting your

eyes in these conditions. Always wear protective eyewear that shields UV

Radiation to protect your eyes from long-term damage. Choose eyewear that

balances color and provides clear vision, so you can accurately assess your

plants. Many products that protect your eyes from UV light and HEV light may

be an economical solution but don’t provide visual clarity that protects

against eye strain and fatigue. Keep your plants and your eyes healthy for

life.