There is no such thing! You are either alive or dead. These are most likely dreams or nightmares.

Sheikh I’ve heard of stories about people who have had ‘near death experiences’ I would like to know the Islamic perspective of such events some people who have had these experiences claim they felt like they were floating, they saw Jesus (alayhi salam), others say they saw old relatives. All these reports came from Kufar and are against Barzakh