One technique that may help you is to try a structured relaxation technique.
The technique I sometimes use is:
Begin by lying down.
Focus on your breathing, and will yourself to slow, deep breathing. Your heart rate should also draw down to your normal resting rate.
Now, close your eyes, and focus on your forehead. Tense all the muscles there, and hold them tensed for a period of about ten to fifteen heartbeats, or three to five breaths. I never found that it matters what the specific period was, but you want it to be something you can keep standard, while relaxing and keeping your eyes closed.
After your period ends, relax the muscles of your forehead.
Repeat the tensing, hold, and release one or two more times. Only tensing your forehead. It’s harder than it sounds, but that’s also part of the key to this - you’re going to be working down your body, tensing muscle groups or pairs of muscle groups in tandem, but only that specific set of muscles, you want to let the rest of your body relax.
All this time I’ve always found I am thoroughly aware of my own breathing, and it’s very easy to keep it at a constant rate.
When you finish with your forehead, move on to your jaw, or cheeks if you prefer. Repeat the same process of tensing, holding and relaxing with your next chosen muscle group.
Slowly work down your body, taking things in as small a group of muscles you feel that you can voluntarily control, by themselves. Tensing, holding, and relaxing each group, and letting it alone once you’ve finished with it.
For myself, by the time I get through with my feet I find I’m thoroughly relaxed, and it is simplicity itself to allow sleep to take me.
I’ve heard this called both self-hypnosis or simply relaxation techniques. No one I’ve ever described it to has ever said it has any dangers associated with it, so even if it won’t help you sleep, you’ll just be out some twenty or thirty minutes, and feeling more relaxed for it.
One more thing, you really have to focus on what you’re making your body do. You can’t be doing this and thinking about anything else for it to work. If you’ll bear me sounding kinda woo-woo, you have to have your mind and body working together on this.
Another possibility is to print out a section of the Code of Federal Regulations to read in bed. (I can recommend 10CFR20, specifically.) Even if it’s something of professional interest to you, the writing in those regs remains a soporific of the first water.