This would be an amazing design for combating SAD. Seung Yong Song designed it as a den.
"I have memories that I made a den somewhere in my house as a child- Under the
table, in the wardrobe, and in the attic- I created my own base and felt
relieved as if I avoided enemies that were actually non-existent. My own secret
space at the moment which was comfortable and protected, better than a huge
mansion, the coziness of the space like a bird's nest isn't what we dream