If this problem occurs as infrequently as once a month, then in all likelihood, there is a problem with your sleeping posture. Sometimes, we have a tendency to sleep wrongly. It is highly likely that you are pressing upon some nerve that is giving you this kind of grief. This is a fairly common cause for the unusual condition you have described. It is also possible that you are somehow biting your cheek while sleeping. It could be that you are keeping your mouth open and then, if your sleeping posture is not really regular, then you end up biting your cheek. Since you have mentioned that the swelling starts with the inside membrane of your cheek and then extends outwards, you would need to examine if you are somehow doing this. However, it is not normal for this condition to remain for 12 hours. In particular, it would probably persist for about three to four hours, by which time the swelling should have subsided. But 12 hours is a long time for the swelling to persist. You should bee seeing a doctor to determine if there is some other matter which is causing you so much trouble.
Only a doctor can tell you if there is any other problem associated with this symptom. In terms of home remedies, all you can do is take care of the swelling. The simplest and most effective temporary measure you can use for this is to apply ice to your cheek. It would be better for you to keep the ice inside your mouth. This will have better results. Another effective method that will take care of the swelling and will also give you relief from pain if there is any would be to make a thick paste of Fuller's Earth and water and apply this to the outer part of the cheek. This will help to bring down the swelling by reducing the temperature of your skin very quickly. This method will also help to keep the temperature down. You can also try to bring down the swelling by massaging your cheek. Be very gentle with this, as you do not want to end up hurting yourself further. If you have it, try to use mustard oil. This is a therapeutic substance and will always help with the healing of the problem as well. If you do not have it, you can always use olive oil too.
answered by M W