This study investigated the effects of 200mg of caffeine on brain activity during sleep in 40 healthy adults, comparing it to a placebo. Researchers found that caffeine increased brain complexity (measured through multiple entropy and complexity metrics) and shifted the brain towards a more critical state during sleep, particularly in Non-Rapid Eye Movement (NREM) sleep. These effects were less pronounced in middle-aged participants compared to younger adults, especially during Rapid Eye Movement (REM) sleep, suggesting age-related differences in how caffeine impacts brain dynamics.
