Complex sentence: The most well-known graveyard slot in most parts of the world is the overnight television slot, airing after late night television and before breakfast television, when most people are asleep and most of those that are awake are at work, away from the television.
Split into simpler sentences: The most well-known graveyard slot in most parts of the world is the overnight television slot, after late night television and before breakfast television. During this time slot, most people that are at home are asleep, and most of those that are awake are at work, away from the television.