MILAN – The importance of a good night’s sleep for the body’s health is proven by science: as the Center for Disease Control and Prevention in the United States has found, one in three adults does not get enough sleep. And the reaction to make up for the accumulated fatigue is often to drink a lot of coffee (or at least take in a lot of caffeine in all its forms). Beware, however, because according to new research developed between Germany and Switzerland, the morning cup could worsen the condition of our already exhausted brain.
Considering that already a single night of insomnia leads to a decrease in the amount of gray matter in the brain (especially in the areas related to memory, perceptions and rational thoughts), one can still only imagine how much this repeated phenomenon might affect the well-being of this organ and how it might attempt to heal itself.
Against all intuition, daily caffeine intake could contribute to the worsening of these nefarious effects of sleep deprivation.
Involved in the trial to probe these two brain mechanisms were 36 subjects of adult age (28.9 ± 5.2 years; F:M = 15:21; habitual level of caffeine intake < 450 mg; 29 homozygous carriers of the C/C allele of rs5751876 of ADORA2A, a variant of the adenosine A2A receptor gene), each of whom underwent a laboratory examination for the duration of nine days.
This period was divided into one adaptation day, two baseline days, five sleep restriction days (allowed just five hours) and one recovery day. During the sleep-restricted period, 19 participants received 300 mg of caffeine in three cups of coffee per day, while the other 17 took the same amount but decaffeinated coffee.
The MRI data
They were obtained at three time points during the study and showed that, compared with baseline, chronic sleep deprivation was associated with increased gray matter in various regions of the brain in the decaffeinated-drinking group.
The researchers think this is indicative of the way our brains adapt to and counteract the negative effects of sleep deprivation.
Conversely, subjects in the group that ingested caffeine showed a reduction in gray matter in these brain regions
In summary, this study revealed reversible cortical plasticity in frontal, temporal-occipital, and thalamic gray matter in response to CSR (chronic sleep restriction).
This plastic response, however, can be suppressed or reversed by concomitant caffeine intake. Individual availability of subcortical A1Rs (adenosine receptors) at baseline may play a role in the gray matter response associated with caffeine. Further studies are needed to more thoroughly investigate the role of A2AR in these GM changes.
The article in the Nature journal, Scientific Reports: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
