Caffeine May Intensify Brain Changes Caused by Sleep Loss: Study

A recent study published in Scientific Reports has found that caffeine might exacerbate the negative effects of chronic sleep restriction on brain structure, specifically gray matter. Conducted at the German Aerospace Center’s research facility, the study sheds light on how caffeine intake during periods of sleep deprivation can lead to greater reductions in gray matter volume compared to those who abstain from caffeine.

Gray matter, crucial for processing information and regulating cognitive functions, has been linked to various mental health issues when its volume decreases. This new research investigated whether caffeine consumption during sleep deprivation exacerbates gray matter loss. The study involved 36 healthy adults, aged around 29 years, who were divided into two groups: one consuming caffeine-containing coffee (CAFF group) and the other drinking decaffeinated coffee (DECAF group).

Over a nine-day period, participants first underwent two baseline days with 8 hours of sleep per night, followed by five days of restricted sleep limited to 5 hours per night, and concluded with a recovery day of 8 hours of sleep. During the sleep restriction phase, the CAFF group received 200 mg of caffeine in the morning and 100 mg in the afternoon, while the DECAF group received equivalent volumes of decaffeinated coffee. To assess the impact on brain structure, participants underwent magnetic resonance imaging (MRI) and positron emission tomography (PET) scans at three intervals: after the baseline period, after sleep restriction, and after the recovery period. Saliva samples were regularly collected to monitor caffeine levels and ensure accurate tracking of its physiological effects.

The results revealed that chronic sleep restriction led to changes in gray matter volume, and these changes were notably influenced by caffeine intake. Participants in the DECAF group showed an increase in gray matter volume in several brain regions, including the prefrontal cortex, temporal-occipital cortex, and thalamus, which are associated with cognitive and sensory functions. This increase suggests a potential compensatory response to the stress of sleep loss. In contrast, the CAFF group exhibited a decrease in gray matter volume in these same regions, indicating that caffeine might inhibit the brain’s ability to compensate for sleep deprivation, thereby worsening the impact of insufficient sleep on brain structure.

The study also highlighted individual differences in adenosine receptor availability, which significantly affected the extent of gray matter changes. Participants with lower baseline levels of subcortical adenosine receptors experienced more pronounced reductions in gray matter volume when consuming caffeine during sleep restriction.

Overall, the study suggested that caffeine may counteract the brain's compensatory mechanisms during periods of sleep deprivation, potentially leading to more significant structural damage.

Reference: Lin, YS., Lange, D., Baur, D. et al. Repeated caffeine intake suppresses cerebral grey matter responses to chronic sleep restriction in an A1 adenosine receptor-dependent manner: a double-blind randomized controlled study with PET-MRI. Sci Rep 14, 12724 (2024). https://doi.org/10.1038/s41598-024-61421-8