Deer are quite nocturnal. I've been woken up by them many times in the witching hours of the night. They frequently act like this and they're always looking for food or the salts in your urine. Making sure you keep those things far away from the tent can help. But they know humans have food and they don't spoke easily at night. It's like they know we're blind at night.

One time, I was convinced there was a bear circling the campsite and progressively getting closer. It was keeping just outside my weak flashlight range, and I was camping in an old native massacre site, so was a little spooked. I fired a couple warning shots, and nothing. 5 minutes later it walked straight up to my tent. I shined my flashlight out expecting the worst and it just walked right past pretty as you please and over to the spot I peed and started munching the leaves there.