Why caffeine can sabotage deep sleep even when you still get eight hours

MedicalXpress | Mai 27, 2026

Evening coffee has sparked controversy for years. Some people fall asleep without difficulty, while others toss and turn for half the night. However, a growing body of research suggests the question of whether coffee makes it harder to fall asleep may be too simplistic. What appears to matter far more is what happens in the brain during sleep.