You are not a fixed thing.  Growth is possible.

When you're tired, your world gets smaller. We go about the world living in different worlds, and the only way we experience our worlds at all is through our bodies. Sleep is not just a luxury, but it is critical to our perception and our ability to go about the world. As our experiences - experiences of thought, emotion, interaction, relationships, (anything really) - is dependent on our body, there is an argument for taking care of your body.