Well, yes, dehydration can be a sign of sunken eyes. And you should know that dehydration is a condition that occurs when the loss of body fluids, mostly water, exceeds the amount that is taken in. when someone has dehydration, there are more water moving out of our cells and then out of our bodies than the amount of water we take in through drinking. In this way, our body can be disordered, and it leads to sunken eyes sometimes. But on the other hand, there are also some other reasons which can cause sunken eyes, such as the lack of sleep and the bad habit. To treat it, you can just have a good rest and drink enough water and eat fruits, so that it can be relieved.