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If you’re in need of an afternoon energy boost to make it through the workday, decaf coffee might not be the first option that comes to mind.
However, if you aim to awaken feeling refreshed, specialists recommend you think again.
Recent studies have discovered that consuming as few as two cups of coffee following midday may be sufficient to transition the brain into a more active and energetic condition during the night, causing disruption to your energy levels.
Researchers from Canada stated that caffeine, one of the most commonly used stimulants globally, can alter the structure and intricacy of brain activity throughout various sleep phases.
Lead author of the studyProfessor Philipp Thölke stated: “The extensive consumption of caffeine by the general population makes this issue a significant health concern.”
“Grasping how caffeine influences sleep patterns and brain activity can shed light on its effects on neural well-being,” he added.
A team of scientists from the University of Montreal examined the sleep quality of 40 individuals who are in good health and consume a moderate amount of caffeine, ranging in age from 20 to 58 years.
Participants stayed for two nights at a sleep clinic, following the consumption of 200mg of caffeine—equivalent to about two cups of coffee—and on another occasion after taking a placebo.
The scientists implemented a double-blind approach, ensuring that they were also unaware of whether the participants had consumed caffeinated or caffeine-free beverages before arriving at the clinic.
The sleep quality of the participants was tracked through an electroencephalogram (EEG), a device that captures brain activity by detecting electrical signals generated by the brain.
By employing a sleep EEG, scientists examined various indicators of brain complexity, analyzing the randomness of brain signals, the ease with which the signal can be compressed, and the stability of the signal over time.
They also examined how electrical activity is spread out among various frequency levels.
The findings indicated that caffeine primarily influenced brain activity during non-REM sleep—the phase of the cycle regarded as the calm or restful period.
This phase is divided into three separate stages: an individual begins to fall asleep, and subsequently transitions from a light sleep state into a deeper sleep.
At this stage, an individual’s respiration, brain function, and pulse usually decrease, body temperature falls, and eye movement ceases.
This is a highly rejuvenating stage that assists the body in mending tissues and muscles while enhancing the immune system.
Nevertheless, scientists discovered that ingesting caffeine following midday had a detrimental effect on this essential phase, leading to less rejuvenating sleep.
‘Consuming caffeine postpones sleep but does not stop it, meaning that although we might fall asleep while under its effect, the brain, and consequently the sleep itself, is affected by the substance,’ Prof Thölke explained.PsyPost.
It results in lighter sleep, with higher levels of information processing occurring during the sleep stages when the brain typically engages in deep, restorative rest.
The scientists also observed that specific brain signals were more level, indicating that when under the effect of caffeine, the brain became more similar to a ‘critical state’—a condition in which the brain is most sensitive and flexible.
They also examined the influence of age on caffeine’s effects on the brain and sleep quality.
In general, individuals between the ages of 20 and 27 were more likely to experience the stimulating effects of caffeine during rapid-eye-movement (REM) sleep than those in middle age.
Scientists proposed that this might be due to older individuals having fewer adenosine receptors in the brain.
A substance known as adenosine accumulates in the brain while we are awake, gradually causing us to experience fatigue.
Caffeine functions by inhibiting adenosine receptors, leading to increased alertness.
The scientists proposed that as older individuals have a reduced number of receptors, the impact of caffeine might be less pronounced, particularly during REM sleep.
Nevertheless, during non-REM sleep, the impact of caffeine remained similar among all age groups.
Therefore, researchers determined that caffeine can alter the brain’s structure and affect the quality of our sleep.
Nevertheless, they admitted that their research involved only healthy people, hence they stated that the results might not apply to those with neurological or mental health issues such as restless leg syndrome or Parkinson’s disease.
A report from The Sleep Charity last year revealed that nine out of ten individuals face some form of sleep issue.
There is a connection between poor sleep and various health issues, such as cancer, stroke, and difficulty in conceiving.
Professionals have previously recommended that experiencing wakefulness during the night does not automatically indicate insomnia, a condition that statistics show impacts as many as 14 million individuals in the UK.
However, lack of sleep has its own consequences, such as irritability and decreased concentration in the short term, as well as a higher risk of obesity, cardiovascular disease, and diabetes.
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