A recent study from the University of Montreal shows that caffeine consumed in the hours before bed can alter the brain’s sleep recovery, especially in younger adults. The research found more wake-like brain activity during sleep when caffeine is used in the evening, potentially hindering both mental and physical restoration. For Thailand’s coffee- and tea-loving society, these findings raise timely questions about late-day caffeine and its impact on well-being.
In Thailand, iced coffee and bubble tea after dinner are common choices for students and professionals burning the midnight oil. The study, published in Nature Communications Biology in 2025, indicates that even moderate evening caffeine can noticeably change sleep rhythms, keeping the brain more alert and less restorative. The effect is strongest among people in their 20s due to age-related differences in brain chemistry.
The Montreal team analyzed sleep with electroencephalography (EEG) in 40 healthy adults across two nights: one after a caffeine dose of 200 mg (roughly two cups of coffee) and one after a placebo. They focused on non-REM sleep, which is crucial for memory and cognitive recovery. Advanced AI methods helped identify subtle changes in brain activity, particularly a reduction in restorative slow-wave theta and alpha waves, and a rise in beta waves associated with wakefulness. The researchers described a shift toward higher neural “criticality,” meaning the brain remains more reactive and less restful during sleep.
Young adults showed the strongest disruptions. Adenosine receptors—targets of caffeine—are more plentiful in younger brains, making them more susceptible to caffeine’s wake-promoting effects. As a senior sleep scientist explains, aging reduces adenosine receptor activity, which partly explains why caffeine’s impact tends to lessen with age.
These insights hold particular relevance for Thailand, where energy drinks, tea, Thai coffee, and caffeinated tonics are woven into daily life. Students preparing for exams, shift workers, and professionals in demanding jobs may inadvertently compromise nighttime recovery through late-day caffeine. Bangkok’s 24-hour culture can translate into nights of restless sleep rather than genuine rest.
EEG traces from the study showed diminished slow-wave activity after evening caffeine, with elevated beta activity signaling alertness. AI analyses confirmed these patterns, suggesting the brain is more dynamic and less synchronized for memory consolidation and recovery. Lead author Philipp Thölke notes that caffeine increases brain signal complexity, especially during sleep stages essential for cognitive restoration.
Practically, this means that late-day caffeine can make it harder to fall asleep and may impair overnight brain recovery and memory consolidation. For Thai students and workers reliant on restorative sleep for performance, these findings point to a need for smarter caffeine planning.
Thailand already faces public health concerns around sleep and stress. A national survey of Bangkok high school students found many report less than the recommended eight hours of sleep, with study demands and caffeine use cited as contributing factors. Separately, the Thai coffee market remains fruitful, with substantial nighttime consumption linked to a vibrant cafe culture. Energy drinks, often high in caffeine, are widely used for stamina and focus, raising additional health considerations for daily life.
The Montreal study underscores the value of integrating neuroscience into public health guidance. While caffeine can boost daytime alertness, its nighttime consequences deserve attention, especially for high-risk groups such as young adults balancing study and work.
To help Thais protect sleep, experts propose practical steps:
- Be aware of caffeine sources beyond coffee, including tea, sodas, chocolates, energy drinks, and herbal blends.
- Prioritize daytime caffeine and reserve evenings for non-caffeinated options that promote relaxation, such as chamomile or pandan-infused beverages, or warm milk.
- Young adults with signs of poor sleep should limit after-dinner caffeine and consider sleep-promoting routines.
Public health and education leaders can share nuanced guidance that respects Thai culture while promoting healthier sleep habits. The goal is to preserve beloved cafe culture while encouraging smarter consumption for better daytime performance and well-being.
If sleep is a concern, consider trying caffeine-free beverages after mid-afternoon and monitoring personal responses. As Thai society evolves in step with science, supporting brain health through smarter sleep practices may prove as essential as the daily cup itself.
Data and insights are drawn from research conducted at the University of Montreal, with implications highlighted by neuroscience and sleep health experts. The study used EEG and AI to measure sleep changes and is part of a broader international discussion on caffeine and sleep.