Merriam Webster's Dictionary defines a Nighthawk as: "a person who habitually is active late at night."

During my early years, I often found myself hyperactive as the sun began to set. I remember cleaning up my room; pondering about Life and Death; often times, spending hours in vain attempts to define myself.

The dark clouded skies... Being awake when all sleep. A brief sensation of loneliness.
I remember nothing else.

Traffic is light during the night, most are asleep and all is quiet. The wee hours of the night, you notice strangers stroll the empty streets outside, as you take another sip of latte in a tiny coffee-shop. The uncustomary, surprisingly soothing atmosphere of a commonly crowded place surrounds you. This is all you need to relax; you speak of dreams and hopes, loves and disappointments. Perhaps because you feel no one is really listening, perhaps some deep desire of self-expression suddenly awakens. You drop your defenses.

I have discovered, a truth universally known, that one can sustain oneself for an extended period of time, with nothing but sugar and caffeine. When sugarhigh, one can discount a sleepless night, savoring the astounding adrenalin rush the following day; collapsing, ultimately, as nightfall approaches. You feel as if you can do anything, survive everything. You are invincible.

Edward Hopper's Nighthawks springs to mind.