Sleepless or endless thoughts: which one comes first?

For me, being able to sleep before 12 at night is a blessing. My sleeping problem reoccurs lately. At the worst time, I would only be able to close my eyes at 5 in the morning. No matter how hard I try, my eyes betray me, they refuse to sleep. Then some time before 8 AM, I would be awake with a heavy head and feeling dizzy. It feels like I walk in the air, my feet do not even touch the ground.

In the sleepless night, there is so much noise in my head, endless thoughts of everything roaming around. I think of all stuffs; work, personal life, family and relatives, financial issues, dreams, rejections, pains, loneliness, even life after death and the list is still on and on.

The sleepless nights always grant me endless thoughts. Or is it the other way around instead?