(1) Work 40 hours a week. (Working more feels like you’re doing more, but you’re actually doing less.) (2) Work below capacity (say 80%) during those 40 hours. (3) Consider spreading 40 hours across 4 days instead of 5. (4) Get the sleep you need; allocate 8 hours. (5) If you need a short productivity boost, work more for 3 weeks. But expect an equivalent reduction in productivity afterwards.
(Full Post: http://venturehacks.com/articles/laws-of-productivity)

Babak Nivi is a co-founder of AngelList and Venture Hacks. Previously, he was an entrepreneur-in-residence at Bessemer Venture Partners and Atlas Venture. He has worked on startups including Songbird, Grockit, and Kovio. He went to school at MIT where received 2 patents and published in Science.