Prologue:

Bilbo could have been sitting in his grandfather's old chair, in his warm Hobbit-hole. Bilbo could have been sipping a cup of hot tea, freshly brewed on his mother's old stove, and Bilbo could have been happy and content, eating his homemade muffins, perfectly seasoned with cinnamon and blueberries. Bilbo could have been comfortable, warm, and happy.

What Bilbo was doing, instead of all the things he actually wanted to, was lying on the ground with his head thumping, and trying, slowly, to get his eyes to start focusing once more.
The world around his was out of place. Rocks and stones, that he knew was there, were now blurry, hazy shapes, hard to properly identify and separate. They were almost seeping into one big grayish shape.
If not for the fact that Bilbo hadn't seen anything but rocks for the last few days, and the fact that he could even feel some of the sharper ones digging their way into his back, he wouldn't be able to get his mind to work properly, and work out what the grey things were.

Bilbo should definitely not close his eyes.

It would be a very poor choice on his part. And Bilbo, mostly, did not make bad choices. He was a sensible Hobbit, a Baggins from Bag End. In fact, he was probably one of the most sensible of Hobbits there was, if you looked past this little adventure he was currently on. A sensible Hobbit, whom simply needed to rest his eyes for a minute.