Personally, when I write something there's around five thoughts buzzing around in my head- sometimes more. They can be relevant or not.
We're always thinking of something, weather it be song lyrics stuck in your head, or you're thinking of someone, you're always thinking.
It bothers me. Because I have a habit of overthinking, and scaring myself into no sleep. then overthinking again, because of sleep deprivation.
Sleep is an anathema to me, because it can go two ways; I sleep for a good seven hours, and have an okay day, or I sleep for three hours, and feel like death itself in the morning.