If you're a regular coffee drinker, you may have experienced the dreaded caffeine withdrawal headache.
It's a painful reminder that caffeine is a drug you can become dependent on — that it doesn't just perk you up, but changes your brain in the process.
"It is addictive," says Llew Mills, a drug and alcohol researcher at the University of Sydney.
"And it has a well-established withdrawal syndrome, as most people who have tried to stop for a little while would know."
Article from ABC Health & Wellbeing