Coffee has been hailed one of the best drinks to start your morning with by many people. Some even claim they can’t get their morning started without their cup of coffee. However, does it actually energize you or does it affect the way your body functions to accommodate more awake hours? Your daily coffee might help you power through the day, but could it be keeping your brain too active at night, even while you sleep? A new study suggests that caffeine doesn't just affect your energy levels; it may also change how your brain works during sleep, especially if you're in your twenties. Caffeine's Impact on Sleeping Brains Researchers in Canada found that drinking caffeine before bed might keep your brain in a more active state all night. This study, published in the journal Nature Communications Biology, utilized electroencephalography (EEG) and artificial intelligence to see how caffeine changes the brain's behavior during rest. The researchers explained that advanced statistical analysis and AI were used to identify subtle changes in neuronal activity. The results showed that caffeine made brain signals more complex, meaning the brain's activity was more dynamic and less predictable. This was especially true during the non-rapid eye movement (NREM) phase of sleep, which is really important for memory and getting your brain ready for the next day. How Super Alert Caffeine State Affect Us The study also found that caffeine boosted something called "criticality." The researchers explain that criticality as a state where the brain is perfectly balanced between order and chaos. In this state, the brain works at its best, processing information well, adapting quickly, learning, and making decisions easily. But this super-alert state isn't good for sleep. While caffeine helps you focus during the day, this heightened state could mess with your rest at night. Your brain might not truly relax or recover. What Caffeine Does to Brain Waves To see these effects, researchers watched 40 healthy adults as they slept. Participants took either caffeine pills or fake pills before bed. The researchers discovered that caffeine increased beta brain waves, which are linked to being awake and mentally engaged. At the same time, it weakened slower brain waves like theta and alpha, which are connected to deep, restorative sleep. These changes suggest that even when you're sleeping, your brain stays more active and less rested if you've had caffeine. Jerbi noted that this change in brain activity might explain why caffeine affects how well your brain recovers at night, potentially impacting your memory. Why Age Matters with Caffeine The effects of caffeine were much stronger in young adults aged 20 to 27, compared to middle-aged adults between 41 and 58. This difference might be because of adenosine receptors in the brain. Adenosine is a chemical that builds up during the day, making you feel sleepy. Caffeine blocks these receptors to keep you awake. Younger adults have more of these receptors, so caffeine has a stronger effect on them. These adenosine receptors naturally decrease, which reduces caffeine's ability to block them and boost brain complexity. This could partly explain why caffeine had less of an effect on the middle-aged participants. Since so many people use caffeine daily to fight tiredness, the researchers say more studies are needed to understand its long-term effects on brain health and to give personalized advice for different age groups.