“You are a human being not a human doing.” (Obey the Sabbath)
Have you read the creation story in Genesis? Have you read the 10 commandments? On the seventh day after creating (working), God rested! He deemed resting so important that He made it one of the commandments!
Ecclesiastes 3 also speaks of various times. “A time to uprootA time to build” It’s very good to work well, but one also needs to give your body a break and rest! That saying “work hard, play hard” needs to have “rest hard” added to it too.
You’re allowed to say no to some invitations. Don’t burn yourself out! And sleep is also a good thing, the Proverbs tell us so here: http://bit.ly/2ASYOoD