Do you snore ? ?
If you have nasal blockage at night and snoring
then two problems may occur--
1. increased chances of reflux only at night while snoring and not during the day
2. dry air goes in through the mouth and cause sore feeling.
If you do not snore then the other possibility can be nasal allergies and post nasal dripping of infected material from nose which causes soreness for this you need to consult ENT specialist
and take medicines
in doubt do reply