It's nothing short of remarkable just how quickly people pick up the spirit of another. They might not be able to pinpoint precisely what is going on with the other person- probably not- but they will have a sense about them which if uncovered, will likely be verified.
This is in part why it's so important for us to keep our spirits open before God, before the Spirit of God. When I say spirit, I mean something of the essence of who we are as far as what animates and moves us. And why we live; what gives us life.
Something in us as humans, made in God's image, surely directly corresponds to the Spirit of God. And it's not just about we as individuals and God. But we together with others, and God. Both.
And while the human spirit can overcome deprivations of the body, like lack of sleep (I'm too experienced in that one!), our whole human person, including our bodies, is important, even to help us in our spirits before God and others. Jesus needed his sleep while on earth, and so do we. At the same time, we can still do well when deprived of basic needs, up to a point. I remember now, Richard Wurmbrand's remarkable testimony about his deprivations while in prison for his faithfulness to Christ.
What do you find helps you in regard to your human spirit? Or what might you like to add here?