Sleep is a vital aspect of our lives. We need it to help fight off illness, to relax, to recoup so we can focus better, to help us retain information better, rejuvenate, repair tissue, grow muscle, to get rid of the waste, to relieve stress, etc. However, so few of us actually get the sleep we really need. We are constantly irritated, not as aware, do not make good decisions, forgetful, etc.
According to God we are to relax, but does He instruct us to sleep? Yes, but it is not as clear as we need to sleep. Gods instructions for sleeping:
Proverbs 3:24 New International Version (NIV)
24 When you lie down, you will not be afraid;
when you lie down, your sleep will be sweet.
Ephesians 4:26 New International Version (NIV)
26 “In your anger do not sin”: Do not let the sun go down while you are still angry,
1 Corinthians 6:19-20 New International Version (NIV)
19 Do you not know that your bodies are temples of the Holy Spirit, who is in you, whom you have received from God? You are not your own; 20 you were bought at a price. Therefore honor God with your bodies.
This could be interpreted a lot of ways, but essentially it is treat your body the way it is supposed to be treated and that includes sleep.
If you want to be at your best, then you need to sleep.