Tomato plant needs some help?

I cannot plant a garden outside due to lack of space and all the deer would eat my plants. However I have stared garden veggies in planters and every day I move them outside and bring them in at night because of the damn deer. I have a tomato plant that is doing alright but every time I put it outside it starts wilting until i bring it back in. Does anyone know why it does that. Its perfectly fine once it is inside.