Indicates someone is sleeping very deeply, usually due to extreme tiredness or exhaustion.

Sleep Intensity

Used to describe someone who is so soundly asleep that they're not likely to wake up easily.

Not Disturbable

The phrase is often used hyperbolically to emphasize just how deeply asleep someone is.

Also used when someone is completely engrossed in an activity and unaware of their surroundings.

Implies deep focus or absorption in a task, leading to a lack of awareness.

Some may think it only refers to sleep, but it also applies to deep concentration.