Infrared light is longer in wavelength than the red end of the visible light spectrum but shorter than microwave radiation. In simple terms, infrared light is what we perceive as heat. We emit it, which is why, according to the NASA website, we can be visible at night to someone wearing night-vision goggles. We also receive infrared light from our surroundings, in particular the sun. Infrared light poses very few dangers and many benefits to our health, but it is also important to acknowledge its potential risks.
Gradual Opacity of the Eye's Lens
When your eyes are exposed to infrared light for lengthy periods of time, the longer wavelengths of this invisible light can damage your eyes. This can happen if you frequently use a welder with inadequate eye protection, for example. At shorter distances, it is more likely that you feel a burning sensation from the light emitted by the welder, and you naturally move away from it to protect your eyes. However, prolonged exposure of infrared light to the eyes, over years, can cause gradual, irreversible blindness.
On a hot day, you might feel tempted to sit in the sun and get a tan. While infrared light itself after a while only causes you to feel overheated, the UV rays that coincide with the sunlight and infrared rays can cause your skin to burn. Your skin produces melanin to a greater or lesser degree, depending on your heredity, to protect its deeper layers, and this produces the darker colour of a tan. But eventually the harmful UV rays can come through to the deeper layers. This is when we perceive the characteristically red, burning sensation we call a sunburn.
Benefits of Infrared Light
Infrared light has far more health benefits than it has harmful effects. It causes you to feel warm when you are exposed to the sun on even a chilly day, and it raises the white blood cell count inside your body, which promotes greater immunity and healing. It is used to diagnose eye diseases by taking detailed pictures of the deep, hard-to-see blood vessels at the back of the eye. As a special source of heat, it is used to treat certain diseases, such as haemorrhoids. It is used as a household source of heat via heaters that emit infrared radiation. This radiation directly warms surrounding objects and bodies, thus being extremely energy-efficient.