It's really up to you and what you feel you can handle. Don't go by what other people can do and rate yourself to their settings. If your body is too exhausted then no, if you feel alright and you know you can handle it safely then do it. Everybody has to make the call for themselves though. Some people just need a nap, and others need more than that. If you are so tired and sleepy you cant think, then call in.