What can be the word for "inner protected world"?

I want to use for this title sentence:

> 
> A guy in his **inner protected world**
> 
> 
> 

It's some sort of mental sanctum.

I want to use it in a positive sense. In my local language we call it *cossetto*, the same as when a worm converts itself into butterfly. In my local language we say that it comes out from its *cossetto*. 

Like I want to use it for a guy who is happy in his own environment , who doesn't worry about the world situated outside .

Please can someone suggest a better word or phrase?