On a hot day there is nothing better than something ice cold to cool you down - whether it's an ice cream or a refreshing drink. But there's also not much worse than the sudden stabbing pain that can suddenly grip your head - known as a brain freeze or an ice cream headache.
The pain is familiar to most of us, although some are more susceptible than others - with those who suffer migraines more likely to get what is properly known as a cold-stimulus headache. The painful reaction, which causes no permanent damage, happens when something very cold comes into contact with the roof of your mouth.
Scientists believe the sudden cold causes tiny blood vessels in the roof of your mouth to rapidly constrict. The pain response that causes as a defence mechanism is transmitted to the brain through the trigeminal nerve, one of the major nerves of the facial area, meaning the brain interprets the pain as coming from the forehead and spreading to the temples.
Other scientists believe the pain is caused by increased blood flow to the brain creating pressure. Scientific research studies have been published in the British Medical Journal and Scientific American.
The sensation is harmless, though unpleasant, and should last no more than 30 to 60 seconds. But if that is too much - there are things you can do.
The first is to avoid cold food or drink touching the roof of your mouth - consume slowly in smaller amounts. If pain does start, some people report that drinking warm water will restore the balance quickly and end the pain.
You can also curl up your tongue and touch the roof of your mouth with the underside - rapidly warming it to end the pain. The term ice-cream headache was first seen in writing in 1937 in a journal entry by Rebecca Timbres.
Brain freeze was first recorded as a phrase in 1991 and is trademarked by 7-Eleven. Cats have been observed suffering brain freeze.
