chug a glass of warm chamomile tea with milk

works for me sometimes

One trick that sometimes works for me is I go to sleep when I feel slightly tired, don't fall asleep, get back up and bull shit myself that I will stay awake all night. Somehow or other, this triggers a "fuck no" reaction in my body almost every time and I feel tired / can sleep within about 20 minutes.

This and/or melatonin.

Cut caffeine 4 hours before bed
Cut food 2 hours before bed
Cut screen time 30 minutes before bed (includes phone, iPad, etc not just computer)

Set up a constant schedule before bed. Should be ~5 minutes long, something you do EVERY NIGHT right before bed. Once you do this activity, the next thing you do is sleep. You don't do anything in between this and sleeping, EVER. If you can't fall asleep, you lie there until you do fall asleep. This is called classical conditioning, and your body will associate this activity with sleeping, so when you perform the activity, you will get sleepy because your body is expecting to sleep. Takes a little while to get going but #1 best way to solve insomnia.

But for the most part you're probably just fucked for a bit. Emotional trauma will do that.

kick the bucket.

Meditation...or GABA agonists.