Caffeine lowers slow‑wave sleep depth as measured by EEG, even when total sleep duration remains unchanged. Electrical activity in the brain shows reduced slow‑wave activity after caffeine intake. People who need caffeine for alertness should be aware that it can compromise restorative sleep quality. The effect varies by dose, timing, and metabolism, so results differ across individuals. sumber: sciencedaily.com/260922005719.htm my other side: setyadi.com