Well, it is much better to have a sick day when you aren't in good shape than go to work, pretend that you are working, make a mess and then go home.
I had difficult times explaining to a former boss of mine that when one is exhausted, he or she performs so badly that it takes more time to repair the damage later, than to postpone the task for a day or two. He just thought that by putting more pressure on us, he can squeeze better results but actually the only results were that the number of people who left the company went on the rise.
