You might expect something unpleasant like tension or hunger to be the most common cause of head pain. In fact, it's something most people are quite fond of: ice cream.

One in three people get "brain freeze," known more formally in the medical community as "ice-cream headache." It occurs when any very cold food or drink hits the back of the palate, leading to a stabbing headache usually felt in the front of the head. Pain peaks 30 to 60 seconds after ingesting the cold substance, and eases in 10 to 20 seconds. In a few unfortunate people, the pain can persist for up to five minutes.

It's an old wives' tale that ice-cream headache happens only in the summer. People are more likely to eat chilly treats in the hotter months, but brain freeze is just as likely to happen when it's cold out.