Do you drink coffee every day? Maybe Monster energy drinks? When you drink it late in the day it might have an impact on your sleep, which in turn may have an effect on your brain. Sleep deprivation can affect the gray matter in your brain, so does caffeine worsen this process? That is what a research team wanted to get to the bottom of.

Researchers conducted a double-blind study on 20 young habitual caffeine consumer participants. They were given tablets to take in two 10-day periods. During one of the periods, participants would be taking placebo tablets, and during the other, 3 x 150mg tablets of caffeine a day, which equals about 3-4 cups of coffee. At the end of each of the periods, the researchers used EEG to quantify sleep quality and also measured gray matter volume.

The results showed sleep depth was no different between conditions.  However, there was a difference in gray matter. The gray matter volume was greater after the placebo period than it was in the caffeine period. One of the areas with the most gray matter reduction was an area of the brain that is essential to memory consolidation.

Results showed that your brain can come back from caffeine induced gray matter reduction, but the researchers caution that “Our results do not necessarily mean that caffeine consumption has a negative impact on the brain,” and “daily caffeine consumption evidently affects our cognitive hardware, which in itself should give rise to further studies.”

Reference: Lin, Y-S., et al. (2021) Daily Caffeine Intake Induces Concentration-Dependent Medial Temporal Plasticity in Humans: A Multimodal Double-Blind Randomized Controlled Trial. Cerebral Cortex. doi.org/10.1093/cercor/bhab005.