The pupil can self-regulate in terms of the light intensity. That is a self-protection for eyes. When the light is strong in the day, the pupil will contract; when in the night, the pupil will dilated for dark light. You can apart from the contact lenses and then check again.
Medicinal eye drops, like mydriatics, can cause the eye to dilate as you get an eye exam. Many drugs and some plants and chemical poisons can also dilate the eyes too. If you are in the above situation, consult a doctor or technician and listen to them carefully.
Well, I have to admit that I want to strongly recommend that you stop wearing contact lenses when there's something wrong with your eyes, anything unusualy could be an indicator of your eye condition. Like you said, your eyes are dilated, and there must be something wrong with them. Thus, you shouldn't take the risk of hurting your eyes. On the contrary, you should go to see a doctor and find out the problem. Do not do anything stupid before you know what's wrong, ok? Anyway, hope everything is alright.