Is it harmful to wear sunglasses all the time? It depends.
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 sunglasses when you don't need UV protection could affect your eyesight in the long run.
Let's look at how sunglasses protect our eyes and why wearing them all the time can could 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 darker than they are. Many of the consequences of wearing sunglasses in excess stem from keeping the pupils dilated for abnormally long periods of time.
Can wearing sunglasses indoors hurt our eyes?
Wearing sunglasses indoors shouldn't harm your vision, but it could tire your eyes, causing eye fatigue. This could in turn cause headaches, blurred vision and increased light sensitivity. This can be particularly true of low-quality sunglasses, which may increase the eye strain you experience due to the poor optical clarity of the lenses.
Additionally, wearing sunglasses too often may 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 typically 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?
It could. 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 can block that morning light exposure and 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 help protect your ability to sleep soundly.
Avoid sunglasses without UV protection
Sunglasses that lack maximum UV protection increase the amount of harmful UV radiation your eyes are exposed to. This can increase your risk of developing eye conditions like cataracts, retinal tissue damage and age-related macular degeneration (AMD).
When shopping for sunglasses, look for sunglasses clearly labeled as UV 400 or providing 100% UVA-UVB lens 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.
