Is it harmful to wear sunglasses all the time? In a word, yes. For example, if you routinely wear sunglasses in dim indoor environments, everything from your sleep schedule to your eyes’ ability to adapt to light variations could be at risk. Sure, most of us probably should wear sunglasses more often than we do — especially outdoors when we need to protect our eyes against damaging ultraviolet (UV) rays. However, wearing shades when you don’t need UV protection can damage your eyesight in the long run.
Let’s look at how sunglasses protect our eyes and why wearing shades all the time can actually cause vision and sleep issues:
How do sunglasses work to protect our eyes?
Your eyes are exposed to less light when you look through a pair of dark-tinted sunglasses. Normally, when ambient lighting is dim, our pupils automatically dilate or expand to allow a larger amount of light into the eye, so that more light can reach the retina. This involuntary reflex allows us to adapt to changing light conditions, making it possible for us to see in near darkness as well as in bright sunlight. This process is controlled by the autonomic nervous system, so it happens without us having to think about it.
Wearing sunglasses triggers the same involuntary reflex, especially indoors, where your brain can perceive your surroundings to be particularly dark. Many of the consequences of wearing sunglasses in excess will stem from keeping the pupils dilated for abnormally long periods of time.
How can wearing sunglasses indoors hurt our eyes?
Wearing sunglasses indoors won’t harm your vision, but it can tire your eyes, causing eye fatigue. This can in turn cause headaches, blurred vision and increased light sensitivity. This can be particularly true of dollar-store sunglasses, which may increase the eye strain you experience due to the poor optical quality of the lenses. Additionally, wearing sunglasses too often will keep your pupils dilated for long periods of time. This exposes your entire visual system to less light and can reduce your retina’s ability to adjust quickly to brighter light conditions.
People with photophobia, or excessive sensitivity to light, may find some relief by wearing sunglasses indoors, but eye doctors discourage it. Wearing sunglasses with dark lenses can make photophobia worse in the long term. It may also cause people who didn’t previously have issues with light sensitivity to develop the condition.
Can wearing sunglasses all the time interfere with sleep cycles?
Absolutely. Our bodies’ sleep and wake cycles are governed by hormones released daily in response to the changing conditions around us. The light-sensitive photoreceptors in our retinas play a vital role in controlling circadian rhythms (physical, mental and behavioral changes that follow a daily cycle).
Light is the principal control of our day to night cycle and influences everything from metabolism to sleep. This means we need exposure to bright daytime light, especially in the morning, to help regulate the quality of our sleep.
Wearing sunglasses throughout the day blocks that morning light exposure and can disrupt your body’s regular sleep rhythms. It’s a bit like staying in a semi-darkened room at all times. Wait until after 9 or 10 a.m. to don those shades if you want to protect your ability to sleep soundly.
Caution: Avoid sunglasses without UV protection
It’s especially important not to wear sunglasses with inadequate UV protection too often, especially outdoors. Wearing shades when you don’t need UV protection can damage your eyesight in the long run. Sunglasses that lack necessary UV-blocking lenses will cause your pupils to dilate. This increases the amount of harmful solar radiation your eyes are exposed to, increasing your risk of developing eye conditions like cataracts, retinal tissue damage and macular degeneration.
When shopping for sunglasses, always look for sunglasses clearly labeled UV 400 or provide 100% protection. You can also have any sunglasses you already own tested by an eye care practitioner to make sure the UV protection from your shades is adequate.