What generates enough energy in you that you willingly work late nights and early mornings?
Of course sleep is important. There is a limit to how often we can burn the candle at both ends. But sometimes we do.
Something gives us the energy. Something keeps us moving.
When we are lucky, it's the work itself. Whether someone assigns it to us or we create it, whether we have a deadline or an inspiration, the right work generates energy. Our passion, our attention, our will power is fueled by good work.
We know now that the brain gets tired from being underused: when it is stimulated, it produces resources.
Eventually you will be tired. You might be really tired. Your body will tell you its time to let unconscious process do its work more quickly than it can while you are awake.
But what a rush it is to work late because you love the work.