I usually just take a nap in one of my classes, after finishing all the classwork for that block ofc. But, I recommend taking melatonin at a reasonable time and kinda coaxing yourself into a comfy position while listening to calm music (I personally like rain noises, white noise, or videogame ambiances)

Skyrim ambiance (Secunda) knocks me out cold.

from someone who has insomnia, melatonin has really helped (extra strength, for me but it varies. you take one and you're asleep within a half an hour,,,that is, if you don't look at any electronics

Could you squeeze in another activity throughout your day to help tire you out? Maybe take a run 🏃🏻‍♀️ in the evening! Hot baths and meditation help calm me down when it’s time for sleep 😴

I've got insomnia and what I have found that helps is getting some exercise in during the day before you go to sleep, read a book, listen to a podcast (its hard for me to find podcasts that are actually interesting for me but I found a few. And there are always those times where it just doesn't work. Also melatonin, ashwaganda also helps some people as well as magnesium.

I find that holding something while you sleep helps you to fall asleep faster. Even if its a stuffed animal, or a small pillow

Body pillows were also a life saver for me.