Can oversleeping cause a fever and headache? I went to the ER yesterday thinking I had meningitis, they did a mono spot, checked my lungs for any liquid that may be causing my oxidation levels to be low, did a CAT scan, tested my blood and tested my pee. Everything looked good, the meningitis test came back negative and the declared it just a viral infection that should be over in a few day (2 or 3) they released me and that night (last night) I was feeling better, my fever dropped to about 100 from 102.6 and I went to sleep and slept throughout the night without a headache, I woke up and my bed was soaked in sweat which, if I remember correctly, is a sign of breaking your fever. I took my temperature and it was 96 but I believe that to be because I was soaked in sweat with both my fan on and the air conditioner low because I checked my temp again and it was back to normal without the help of ibuprofen. I then took a nap, after a great night of sleep, and woke up with a headache and a fever of 100.1. So is oversleeping the cause of this headache and fever or do you think my viral infection still present?