Soporific
Developing any skill requires feedback: information about how you’re doing, preferably while you’re in the act of doing it. Sleep does not work this way. With sleep, you lie very still and wait, and if everything goes well you wake up later and don’t remember much. It feels like the opposite of skill.
Sleep does seem to benefit from ritual and preparation—good “sleep hygiene”—like refraining from certain things just before bed: caffeine (a stimulant), alcohol (a depressant), eating a big meal (which makes you tired), exercise (which makes you very tired) and bright lights (which make you squint your eyes). So finding a ritual that makes you relaxed and “ready for sleep” is something that can be refined, as long as it doesn’t involve eating or drinking or doing anything. So at the end of the day (literally), a sleep ritual can be somewhat hit and miss, which occasionally leaves you in the dark (literally and metaphorically), wondering what to do next.
I’ll offer something that seems like technique but probably isn’t: observing and manipulating your breath. Look, you’re already lying still in the dark, so you’re like 85% of the way there—you just need to do the sleepy part now. The only other thing you can control is your breath: you can try to breathe like you do when you’re asleep. You can focus on the rising and falling of your chest and try to imagine or remember what the rhythm of your breath is when you’re very relaxed; and you can try to simulate it. With any luck, you can focus on trying to slow down and lengthen each breath so much that you eventually sink into that deeper level of relaxation and find yourself…