A loss of awareness of the physical body and physical world, and various phenomena may manifest such as visions, sounds, etc. Perhaps it's the hypnogogic state or similar, but some sources suggest it gives access to the subconscious mind.
You're less caught up by external influences that may distract or pain your mind. IIUC you're in a introspective state, exploring your sensations, ideas and emotions.
Grief forced me to learn that, it's an effort at first, and absurd because you're forcing not to move mentally, in the end you drop most your thoughts and a calmer part of you may fill the room.