Fashion icon and Vogue editor-in-chief Anna Wintour took a lot of heat in 2018 when she was seen in the audience of Queen Elizabeth with her trademark sunglasses still on her face. It is apparently rude to be in the presence of royalty with your eyes covered. Ironically, Wintour is rarely seen without her oversized shades. Have you ever wondered why?

In an interview with Insider magazine’s Alison Millington, Wintour explained several reasons she prefers to wear her sunglasses at all times. She admitted that they may have become a crutch at her age, but she is content to continue wearing them anyway.

Based on the Wintour interview and things we have learned from other celebrities, here are five reasons to never remove your sunglasses except when it’s time to go to sleep:

1. They Hide Your Thoughts

It has been said that the eyes are the window to the soul. There is some truth to that sentiment. It turns out that’s one of the reasons Wintour wears her sunglasses nearly everywhere. She says they hide what she’s thinking. Wintour cited the example of sitting in a show and being incredibly bored. No one else needs to know that she would rather be somewhere else. Wearing her sunglasses hides her boredom quite well.

2. They Hide Your Fatigue

Another reason for wearing shades is that they hide the signs of fatigue that show up in and around the eyes. No one will know that you didn’t get enough sleep just by looking at your face. And if you’re fatigued due to illness, a good pair of dark shades can keep you from looking ill to other people. They might even make you look healthy.

3. They Give You Confidence

Setting aside the Wintour interview for the moment, did you know that some people wear sunglasses because they boost confidence? Famous singer and songwriter Roy Orbison is a good example. The first time Orbison performed on stage he was so terrified that he wore a pair of dark sunglasses just to get through the ordeal. After that, he rarely appeared in public without them. He claimed the sunglasses gave him the confidence to perform.

4. They Are Part of Your Personality

Our next reason is more aesthetic than anything else: sunglasses may be a part of your personality. They certainly are in Wintour’s case. Her personality is so intrinsically linked to her oversized shades that she doesn’t seem the same person without them.

5. They Are a Medical Necessity

Last but not least, you may have to wear your sunglasses during every waking hour because they are a medical necessity. Utah-based eyewear designer Olympic Eyewear points out examples like U2’s Bono and the late football coach Tony Sparano.

Bono suffers from glaucoma, so his eyes are especially sensitive to light. As for Sparano, he was injured as a teenager while working in a fast food restaurant. He wore sunglasses constantly to prevent further damage to his eyes.

In her interview, Wintour noted that she was recovering from recent eye surgery. She cited the surgery as yet another reason to not remove her sunglasses. The obvious implication was that no one needed to know of her surgery or how she was feeling because of it.

Most of us wear our sunglasses outdoors on sunny days. That is good enough. But there are others who seem to wear their shades at all times, regardless of the amount of sunlight or the environment they find themselves in. Why they do it is anyone’s guess. But we now know that there are actual reasons.