Sometimes this happens to me, I just can't sleep. I'm I stressing about anything? No. Did I sleep in the daytime? No. Physically having trouble? No. Allah knows why.
Sometimes I can't sleep for days. Once for 4 days, I was continuously waking. To force me to get to sleep, for four days I worked non-stop. So, that my body physically became tired and fall asleep.
Maybe this is why people get addicted to sleeping pills.