There are some sleeping rooms in the Business Lounge over by the hallways to the bathrooms and showers. You can also find some open relaxation rooms on the wall away from the windows by the buffet. I would expect there are some sleep rooms in the First Class Lounge as well, haven't been there when I really needed to take a nap so I haven't looked for sleeping rooms. If things aren't busy you can nap in the open by the windows in some open private space rooms.