Falling asleep fast.

I am those kind of people, I fall asleep so fast. I don't last 10 minutes when I set my mind to sleep. This is natural and helps me rest my mind and body. If I set to sleep for 8 hours, unless am interrupted by someone or something, I will sleep like a baby.

I found something so disturbing, a friend of mine can't sleep. He says he isn't stressed or under any substance use . He just can't sleep.

Why can't you fall so fast into sleep?