It's actually helpful
University of Montreal
Caffeine is not only found in coffee, but also in tea,
chocolate, energy drinks and many soft drinks, making it one of the most widely
consumed psychoactive substances in the world.
In a study published in April in Nature
Communications Biology, a team of researchers from Université de Montréal
shed new light on how caffeine can modify sleep and influence the brain's
recovery -- both physical and cognitive -- overnight.
The research was led by Philipp Thölke, a research trainee
at UdeM's Cognitive and Computational Neuroscience Laboratory (CoCo Lab), and
co-led by the lab's director Karim Jerbi, a psychology professor and researcher
at Mila -- Quebec AI Institute.
Working with sleep-and-aging psychology professor Julie
Carrier and her team at UdeM's Centre for Advanced Research in Sleep Medicine,
the scientists used AI and electroencephalography (EEG) to study caffeine's
effect on sleep.
They showed for the first time that caffeine increases the
complexity of brain signals and enhances brain "criticality" during
sleep. Interestingly, this was more pronounced in younger adults.
"Criticality describes a state of the brain that is
balanced between order and chaos," said Jerbi. "It's like an
orchestra: too quiet and nothing happens, too chaotic and there's cacophony.
Criticality is the happy medium where brain activity is both organized and
flexible. In this state, the brain functions optimally: it can process
information efficiently, adapt quickly, learn and make decisions with
agility."
Added Carrier: "Caffeine stimulates the brain and
pushes it into a state of criticality, where it is more awake, alert and
reactive While this is useful during the day for concentration, this state
could interfere with rest at night: the brain would neither relax nor recover
properly."
40 adults studied
To study how caffeine affects the sleeping brain, Carrier's
team recorded the nocturnal brain activity of 40 healthy adults using an
electroencephalogram. They compared each participant's brain activity on two
separate nights -- one when they consumed caffeine capsules three hours and
then one hour before bedtime, and another when they took a placebo at the same
times.
"We used advanced statistical analysis and artificial
intelligence to identify subtle changes in neuronal activity," said
Thölke, the study's first author. "The results showed that caffeine
increased the complexity of brain signals, reflecting more dynamic and less
predictable neuronal activity, especially during the non-rapid eye movement
(NREM) phase of sleep that's crucial for memory consolidation and cognitive
recovery."
The researchers also discovered striking changes in the
brain's electrical rhythms during sleep: caffeine attenuated slower
oscillations such as theta and alpha waves -- generally associated with deep,
restorative sleep -- and stimulated beta wave activity, which is more common
during wakefulness and mental engagement.
"These changes suggest that even during sleep, the
brain remains in a more activated, less restorative state under the influence
of caffeine," says Jerbi, who also holds the Canada Research Chair in
Computational Neuroscience and Cognitive Neuroimaging. "This change in the
brain's rhythmic activity may help explain why caffeine affects the efficiency
with which the brain recovers during the night, with potential consequences for
memory processing."
People in their 20s more affected
The study also showed that the effects of caffeine on brain
dynamics were significantly more pronounced in young adults between ages 20 and
27 compared to middle-aged participants aged 41 to 58, especially during REM
sleep, the phase associated with dreaming.
Young adults showed a greater response to caffeine, likely
due to a higher density of adenosine receptors in their brains. Adenosine is a
molecule that gradually accumulates in the brain throughout the day, causing a
feeling of fatigue.
"Adenosine receptors naturally decrease with age,
reducing caffeine's ability to block them and improve brain complexity, which
may partly explain the reduced effect of caffeine observed in middle-aged
participants," Carrier said.
And these age-related differences suggest that younger
brains may be more susceptible to the stimulant effects of caffeine. Given
caffeine's widespread use around the world, especially as a daily remedy for
fatigue, the researchers stress the importance of understanding its complex
effects on brain activity across different age groups and health conditions.
They add that further research is needed to clarify how
these neural changes affect cognitive health and daily functioning, and to
potentially guide personalized recommendations for caffeine intake.
Materials provided by University of Montreal. Note:
Content may be edited for style and length.
