Asalam
Don't know if it's effective but many people claim that drinking a glass of warm milk before bed. I never tried, dont like milk though.
When I was 18 I could sleep 24hours straight & even more, until I reached age of around 22?
Now it's a bit difficult for me to sleep, because in some days I imagine alot
alot of imaginations & thinking just anything
then I discovered that nice Islamic videos like "Prophet Muhammad,
it has 12parts in youtube" can make me sleep in no time delay
I can watch in almost everyday just scrambling which part i'll watch the night.
But the problem is that when you move alot when you're asleep, laptop is not advisable to keep beside so, yah reading is also good. and try to calm your mind.