It's when you are awake but your mind is sleeping. It's when you can see but not understand, hear but not listen, walk but collapse.
When you try to fool yourself that the four hours you spent rolling and crying yourself to sleep in bed are enough to get you going long enough, just long enough for the workday. When you try to enjoy the morning sun and wish you had been born a morning person, only the will of God could have changed this unalterable passion for night.
When you put plans and schemes to set your biological hour back in motion and think of sleeping in the afternoon but know it will keep you awake for the night, think of sleeping at their decent hour but know you will be surrounded by past failure and misery or a burning desire for him, think of sleeping before the dawn but know you will not be able to wake up for work, and not think about concentrating on anything because you already know it's a waste of time.
When you show up late for work and apologise, when you miss work and apologise again and again, when you beg and plead everyone not to think you're lazy or faking it. When you smell the coffee and listen to Coldplay in a desperate attempt to freshen up only to find the curtains being closed will you, nill you.