If biting into icecream gives you a headache, blame a rush of blood to the head.

The so-called "brain freeze" - the pain experienced when very cold food or drink hits the roof of your mouth - has long baffled scientists. But they may have arrived at an explanation, in a development that could lead to a flood of new headache treatments.

Most headaches are hard to study, partly due to their unpredictable nature. But icecream headaches are easy to trigger, and can be examined in a laboratory from start to finish.

A team from Harvard Medical School did just that, tracking blood flow to the brain as people drank ice-cold water.


The participants said they felt pain as their anterior cerebral artery opened up, filling the brain with blood. The pain receded when the artery constricted, the Experimental Biology conference heard.

Researcher Jorge Serrador suggested that the rush of blood is a defence mechanism.

"The brain needs to be working all the time," he said.

"It's fairly sensitive to temperature, so [the artery] might be moving blood to make sure the brain stays warm."

He added that the process also appears to raise pressure in the skull, causing pain. When the artery constricts to stop this pressure reaching dangerous levels, the pain eases.

Finding ways to control blood flow to the brain could lead to better treatments for other types of headaches such as migraines, the expert claimed.