Why sleep?

If a man sleep, it should not be for pleasure, but to rest the body in order to do better, to speak better, to explain more beautifully, to serve the servants of God and to prove the truths. When he remains awake he should seek to be attentive, serve the Cause of God and sacrifice his own stations for those of God. When he attains to this station, the confirmations of the Holy Spirit will surely reach him, and man with this power can withstand all who inhabit the earth.

-Abdu'l-Baha

https://bahai.works/Pattern_of_Bah%C3%A1%E2%80%99%C3%AD_Life/Text