It depends. They are recommended outdoors to protect your eyes from the harmful ultraviolet (UV) rays. Proper sunglasses should provide 100% protection or be labeled UV 400. However, sunglasses without adequate UV protection should not be worn for long periods outdoors because they cause your pupils to dilate, increasing the likelihood of developing serious conditions like macular degeneration, cataracts, and damaged retinal tissue. Wearing sunglasses indoors when you do not require UV protection is equally harmful to your eyes in the long term. They will affect your eye’s ability to adapt to light variations and may cause eye fatigue, headache, blurry vision, and photophobia (increased sensitivity to light). Although they provide relief to people with photophobia, sunglasses should not be worn because they may worsen the condition. Prolonged use of sunglasses can also interfere with your sleep patterns.