[tartoran]

You need to learn to wind down. You can't expect to use your brain intensely and then shut off. But you can start by lowering the light, relaxing, stop using electronic devices, etc. (though listening to something unexciting does induce sleep). I also induce sleep by forced repeated yawing. Every couple of forced yawns trigger a real one, and with that some sleepiness. Another exercise I do is to imagine I lift my arms/legs up and let them fall by my side, helps me to relax my nervous system. I've done some meditation in the past and it helped as well but I don't actively do it before bed but you can absolutely try. Another thing that may or may not work for you is white/pink/brown noise. I prefer quiet if I could get it, sometimes that is impossible, e.g. having a window facing car traffic so in that case white noise can reduce the intensity of sudden sounds. So there is no formula but a bunch of habits really do help.