Dreaming of Coffee: Caffeine's Nocturnal Effect
For many, coffee is an essential part of their everyday routine as they kickstart their day with a cup of joe in the morning, and perhaps another in the afternoon to sharpen the mind and refocus on the tasks at hand. Caffeine’s effects on the mind during the day are well-understood, however its night-time influence continues to remain a mystery. In an effort to remedy this, researchers from the Université de Montréal published a recent study on how coffee alters brain activity while we sleep, and how this varies across the ages.
Caffeine is the world’s most widely consumed psychoactive stimulant, a chemical substance that increases activity in the central nervous system. It works by blocking adenosine, a neurotransmitter that promotes sleep and drowsiness by slowing down heart rate, and binding to the same receptors. This temporarily keeps sleepiness at bay and boosts concentration and alertness. Adenosine, however, is extremely important to getting a good night's rest, and the influence of caffeine can have lingering effects on the brain at night.
In order to better understand these effects, researchers collected and analyzed the electroencephalograms (EEGs) of 40 adults aged 20 to 58 as they spent two nights in the lab, one after taking roughly 2 cups of coffee worth of caffeine and another after taking a placebo. They directly compared the data collected during rapid eye movement (REM) and non-REM (NREM) sleep in order to examine the effects of caffeine on brain complexity and what was termed as “criticality,” which is a state at which the brain operates in an optimal balance between order and randomness in order to maximize information processing.
Caffeine is the world’s most widely consumed psychoactive stimulant, a chemical substance that increases activity in the central nervous system. It works by blocking adenosine, a neurotransmitter that promotes sleep and drowsiness by slowing down heart rate, and binding to the same receptors. This temporarily keeps sleepiness at bay and boosts concentration and alertness. Adenosine, however, is extremely important to getting a good night's rest, and the influence of caffeine can have lingering effects on the brain at night.
In order to better understand these effects, researchers collected and analyzed the electroencephalograms (EEGs) of 40 adults aged 20 to 58 as they spent two nights in the lab, one after taking roughly 2 cups of coffee worth of caffeine and another after taking a placebo. They directly compared the data collected during rapid eye movement (REM) and non-REM (NREM) sleep in order to examine the effects of caffeine on brain complexity and what was termed as “criticality,” which is a state at which the brain operates in an optimal balance between order and randomness in order to maximize information processing.
Caffeine does not clock out at bedtime - it keeps the sleeping brain alert and stirs it into restless motion.
Image Source: Cottonbro Studio
It seems natural that caffeine would push the brain towards a more awake state, even during moments of rest. However, this was concluded to go hand in hand with an increase in brain complexity across several measures, especially during NREM sleep, the brain’s main memory consolidation phase. The EEG signals showed more diverse neural activity as well as a flattening of the brain’s power spectrum slope, which is a marker linked to increased neural excitation and reduced inhibition, indicating that the brain was more active and less stable during sleep when under the effects of caffeine. Younger adults, in particular, were affected more pronouncedly by caffeine than older adults, attributed to the gradual decline in adenosine receptors as one ages.
This study adds a new layer to what is known about caffeine. While the short term benefits, including alertness, improved focus, and a burst of energy, are clear and well-known, its nighttime effects come at a cost, especially for younger populations. Caffeine’s ability to alter natural brain patterns and activity during sleep could undermine the brain’s ability to remain healthy and resilient. Coffee is a daily habit for much of the world’s population, so understanding the underlying effects of caffeine is imperative to guiding informed decisions about what individuals put into their bodies.
This study adds a new layer to what is known about caffeine. While the short term benefits, including alertness, improved focus, and a burst of energy, are clear and well-known, its nighttime effects come at a cost, especially for younger populations. Caffeine’s ability to alter natural brain patterns and activity during sleep could undermine the brain’s ability to remain healthy and resilient. Coffee is a daily habit for much of the world’s population, so understanding the underlying effects of caffeine is imperative to guiding informed decisions about what individuals put into their bodies.
Featured Image Source: Chevanon Photography
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