Why do we sometimes feel groggy even after a full night’s sleep?

Morning grogginess, often called sleep inertia, happens because your brain is still transitioning from sleep to wakefulness. This can occur if you wake up during a deep sleep stage or if your sleep cycle is disrupted. It usually lasts from a few minutes to half an hour, but in some cases, it can persist longer. Factors like sleep quality, timing, and even what you ate the night before can influence how groggy you feel when you wake up.