“Caffeine works by blocking the effects of an inhibitory neurotransmitter in the brain called adenosine. This results in increased neuronal firing in the brain and an increase in the release of other neurotransmitters like dopamine (one of your ‘happy’ hormones) and noradrenaline (which makes you feel alert). That stimulates your sympathetic nervous system response – that’s your stress response,” says Dunn.

Interestingly, not all caffeine is made the same. “Matcha tea actually has more caffeine in it than a standard cup of coffee. But it also contains an amino acid called L theanine which actually has quite a calming neuromodulating effect on the brain. So it actually has a sort of an opposing effect to caffeine,” she says.

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