Never do this before bed. It leads to an increase in so-called "criticality"

When did you drink your last coffee? While it helps with concentration, caffeine taken before bed can keep your brain alert even during sleep.

Caffeine is with us every day, and some people can't start their day without it. However, new research by specialists from the University of Montreal shows that its consumption in the evening can disrupt key processes that occur in the brain during sleep .

A team from the Cognitive and Computational Neuroscience Laboratory conducted a study in which they recruited 40 healthy volunteers. During the study, their brain activity was analyzed over two nights: after consuming caffeine and after a placebo.

EEG recorded the daredevils’ nocturnal neural activity, and artificial intelligence analyzed subtle patterns.

- We used advanced statistical analysis and artificial intelligence to identify subtle changes in neuronal activity, said team leader Philipp Thölke .

Illustrative photo / photo: Unsplash, Gabi Miranda

The study found that under the influence of caffeine, the brain enters a state of increased activity and reduced regeneration .

The so-called complexity of the EEG signal increased, and the recording of neuronal activity resembled the state of wakefulness more than sleep . An increase in the so-called criticality, i.e. the state of the brain between chaos and order, was also observed.

- It's like an orchestra: too quiet - nothing happens, too chaotic - we have cacophony. Criticality is the golden mean , where brain activity is both orderly and flexible. In this state, the brain functions optimally: it can process information effectively, adapt quickly, learn and make decisions - explains Prof. Karim Jerbi .

While this state is desirable during the day, it can be problematic at night. The brain is unable to relax or regenerate properly.

The EEG also showed a decrease in theta and alpha waves, which are important for regeneration and memory, and an increase in beta activity , characteristic of the waking state, which would suggest that even during sleep, the brain under the influence of caffeine remains in a more active, less regenerative state.

Illustrative photo / photo: Unsplash, Laura Seidlitz

This was most noticeable in people aged 20–27. The younger brain contains more adenosine receptors , which are blocked by caffeine.

" Adenosine receptors naturally decline with age, which weakens caffeine's ability to block them and influence brain complexity, which may partially explain caffeine's weaker effect in middle-aged participants," says psychologist Julie Carrier .

It turns out that evening espresso not only delays falling asleep but also worsens the quality of sleep. Especially in people under thirty.

The study was published in Nature Communications Biology .