Caffeine consumption may reduce deep sleep brain activity

A review of 32 studies conducted between 1980 and 2024 indicates that caffeine consumption can alter brain activity during sleep, even if the total duration of sleep remains unchanged. Using electroencephalography (EEG) to measure electrical activity, researchers found that caffeine reduces low-frequency brain waves associated with deep, non-REM sleep. Instead, caffeine promotes faster brain activity patterns more characteristic of wakefulness.

Caffeine functions by temporarily occupying adenosine receptors. Adenosine builds up throughout the day to create sleep pressure, but caffeine prevents it from binding to these receptors. This effect can persist even after a person falls asleep, leading to less restorative rest. The impact varies significantly based on individual sensitivity, age, dosage, and timing of consumption.