Is a person who is asleep aware of what is happening around him?

No, a person who is asleep is generally not aware of their surroundings. During sleep, especially in deeper stages, the brain is less responsive to external stimuli, which means that most sounds, movements, or events occurring around them go unnoticed. However, some individuals may experience brief moments of awareness or respond to certain stimuli, like loud noises, but this is not typical of all sleep stages.