Actually, it's not.
According to our top-secret, totally-not-made-up research team, sleeping is just a fancy way of saying "you're not doing enough productivity-boosting activities".
Want to see our findings? Check out our study on "The Correlation between Snoozing and Procrastination" at Myth 2 Study Results.
Or, if you're feeling particularly adventurous, try "Sleeping on the Job: A Guide to Maximizing Productivity" at Myth 2 Sleeping On The Job.