It depends on the frequency and time. I haven't heared of any mental problems that are caused by wearing sunglasses. However, wearing sunglasses too often and for too long will cause some vision problems and eye problems. Firstly, after wearing the sunglasses, the contrast ratio of different things are lower. To see things clearly, people will look things hard. Eyes will be tired quickly. Gradually, the eyesight will be worse. Secondly, ultraviolet rays are to be absorbed first then, they can be sent out. As a result, pupilla would be under the circumstance of much light first and then darker later. That's why some people feel uncomfortable as they wear sunglasses. Many patients have vision problems because they wear sunglasses for 6-8 hours a day and they even don't take off sunglasses when they are in houses. As for your situation, you seem not to wear sunglasses too often, I think if you can control your time for wearing sunglasses, it won't be a big deal.