Caffeine Disrupts Brain Activity During Sleep, Study Shows

A recent study discovered that a moderate level of caffeine is capable of keeping the brain in a state of wakefulness during the night. Researchers asked 40 healthy adults to spend two nights in a laboratory: one night they were given 200 milligrams of caffeine several hours prior to going to bed, and the other night a placebo. EEG scans showed that the sleeping brain was pushed into a state of "criticality" by the caffeine, characterized by more elaborate signals and not complete relaxation.

These effects were most potent during non-REM sleep, the restorative phase of memory and cognitive recovery. Respondents registered fewer slow waves of restorative rest and quicker waves of wakefulness. Young adults aged between 20–27 demonstrated more severe disruptions compared to 41–58 years old, most likely because they have more receptors for adenosine, which caffeine blocks.

Despite advice that consumption of as much as 400 milligrams of caffeine a day is safe, in the study, even moderate use can prevent night brain restoration. If adenosine accumulates to cause sleep, the blockade produced by caffeine can extend wakefulness throughout the night, reducing sleep. With as many as 94% of adults consuming caffeine, possibly many are unknowingly sacrificing sleep.

The findings point to possible consequences beyond memory and cognitive health, suggesting further investigation and personalized guidance for optimal use of caffeine and preservation of sleep quality.