I wouldn't be surprised if the same were happening in the States. I don't believe people can be super-productive more than 5 hours a day unless they work on something they are passionate about or are on drugs.
From my experience, just walking away from a difficult problem, taking time to walk in the forest, relax on the beach, playing sports with friends, doing completely unrelated relaxing things with total focus often leads to sudden inspirations on how to tackle difficult problems. It's like life is telling me to relax and rewards me with great ideas that can be immediately executed, for being just well balanced.
I remember flying with one US businessman between Hawaiian islands, and he curiously asked me how many vacation days do I have - when I told him it's 6 weeks, he went on to complain about how crazy is it in the States, with average of 8.5 day or so of vacation per year.
People, please live your lives!