There's been a bit of a resurgence in news stories about how people who work fewer hours are more productive, and then the rebuttals that say they were only more productive because they knew people were watching and it was novel, but when people aren't watching any longer they slip back into old habits.
I'm not going to argue for a shorter workday here, mostly because I'm lucky enough to be able to define a great number of my days, working remotely, guarding my schedule so the meetings don't continue to multiply like rabbits and coat hangers. It means I'm a better worker when I work remotely, because I can fit in a trip to the gym or a nap when it makes sense to do so, rather than around the edges of my day, or worse, not at all.
But it also means that some of my work days run really long. Aside from a trip to the gym (a nice 2.5 hour break) and a shower a few hours later (a nice 45 minute break), I've either been doing work work or class work. I was sitting here looking at the next book I have to read, wondering what to write tonight, when I realized I'll be more productive tomorrow if I'm actually rested. So I'm off to bed with a moderately trashy novel instead of a business book for the first time in weeks.