What happens when you take too much caffeine

This difference is largely because of the genetic variants in the CYP1A2 enzyme in our bodies, which represents more 90% of caffeine metabolism, Cornelis says.

This is often broken down into two categories of people: caffeine responders, and non-responders – and it’s likely you know which category you fall into. Most people’s coffee-drinking habits tend to match up to their genetic predisposition, Cornelis says, because we’re good at figuring out how many coffees we can tolerate, and sticking within our individual tolerance levels.

But this is where the health benefits associated with caffeine become more complicated.

“Those who metabolise coffee quickly may need to consume more to get the health benefits, because it’s gone so quickly,” Cornelis says.

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Our genetic differences may also affect the extent to which habitual coffee consumption can promote health benefits.

“Some people may develop high blood pressure from drinking caffeinated drinks, some don’t,” says Ruani. “Some benefit from the heart protective benefits of caffeine, and some may not.”

And this may contribute to some of the contradictory findings associated with coffee’s health benefits, she says.

How should you consume caffeine?

Caffeine is a unique drug because it’s so readily available. But this makes it all the more important – albeit, perhaps, more difficult – to consume in moderation.

If you’re struggling to relax and feeling edgy, you may have hit your caffeine limit, says Bailey. But the real telltale sign, he says, is struggling to sleep at night.

“Always refuse coffee at the end of an evening meal, and ask for decaf instead,” he says. “Sleep is so important for the brain.”

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