Can people usually tell when they are about to fall asleep?

People generally do not have a clear awareness of when they are about to fall asleep. As an individual starts to transition from wakefulness to sleep, they often experience a gradual decrease in alertness and responsiveness, and this change can happen quite suddenly. This phenomenon is influenced by various factors, such as fatigue, the time of day, and the person's level of engagement. Consequently, by the time someone recognizes that they are feeling drowsy, they may already be close to falling asleep, leading to a lack of awareness about that impending state.

Understanding this concept is crucial for drivers, as it highlights the importance of being attentive to signs of drowsiness, which can occur without conscious recognition, especially on long trips or during monotonous driving conditions. Recognizing early symptoms of fatigue is vital to ensuring safety on the road.