The science behind the ‘brain freeze’

The ‘brain freeze’ is caused by increased blood filling up your brain and causing intracranial pressure. Selina Haefeli explains.

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It’s a boiling hot day, and you have just gotten your hands on a big fruity flavoured slurpee. You put the straw to the roof of your mouth and start guzzling down the icey, sugary goodness with unstoppable, speedy slurps.

And right in the midst of your joy, a sharp and shooting headache comes on, making you want to scream out in pain. It’s a ‘brain freeze’. Also known as an ice cream headache, frigid face, freezie, shake-ache or, if you’re in to knowing the technical terms for things, sphenopalatine ganglion.

We all know the feeling, but what exactly is going on in your brain that causes such intense discomfort, and why does it come and then disappear so quickly?

Scientists from Harvard Medical School and National University of Ireland in Galway have recently found that brain freeze is associated with increased blood flow to the brain. In the study, 13 healthy volunteers were recruited and made to drink ice-cold water through a straw. They were told to raise their hand at the onset of the headache, and then again once the pain disappeared. Meanwhile, the researchers monitored the volunteers’ cranial blood flow using an ultrasound, and found that more blood was entering the brain during brain freeze via a large blood vessel called the anterior cerebral artery (ACA) – located just behind the eyes, between the two hemispheres of the brain.

The authors of the study suggest that the increase in blood flow could be associated with a self-defence mechanism, where the body is trying to move more warm blood into the brain in response to the cold substance ingested.

Jorge Serrador, co-author of the study, said “the brain is one of the relatively important organs in the body, and it needs to be working all the time”. So when an icy drink hits the roof of the mouth, this triggers a signal to increase vascular supply to the brain, to make sure it doesn’t freeze and loose energy.

Although your body is trying to help, by putting its survival instinct into action, the large volume of blood flowing into the brain causes increased pressure inside the skull, which we interpret as that familiar sharp, debilitating pain.

So next time you’re trying to enjoy a slurpee or some nice ice cream and get a sudden, unbearable headache, remember that the ‘brain freeze’ exists to protect your brain from actually freezing. There’s a difference.

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