Was about to mention yotel - I loved my stay in my yotel at gatwick. Stayed in a similar 'tinyroom hotel' in Moscow last year - it wasn't as nice as Yotel.
My only complaint is not really with the concept itself, it's just that I'm generally using these things, I'm nervous I'll sleep too long and miss my flight.
http://www.yotel.com/Hotels/London-Gatwick/Sleep
https://en.wikipedia.org/wiki/YOtel