I am not an anything, but allergies can cause inflammation in your nasal passages, which results in post-nasal drip. Post-nasal drip is where you get a lot of mucus being produced that drips down the back of your throat, which can make you cough or get a sore throat. It's pretty bad when you're lying down and asleep.

For me, when I have to deal with seasonal allergies, if I am feeling particularly bad that night, I will take an allergy pill to make sure I don't wake up with a sore throat.