When something cold touches the roof of your mouth on a hot day, it may trigger a cold headache, or what in some cases is referred to as brain freeze. The sudden, cold temperature causes sensitive nerves at the back of the throat or a nerve center located above the roof of your mouth to signal blood vessels to dilate, resulting in sharp, throbbing pain. Luckily the pain disappears in 30 seconds up to a few minutes. To prevent this happening, eat slowly, and try to keep the ice cream towards the front of your mouth, then swallow after it has warmed. Interestingly, there have been some experiments about this type of headache. It has been found that the headache could be provoked only in hot weather. Attempts to reproduce the pain during the winter were unsuccessful.