I always wondered why people would suggest "counting sheep" as it seemed like something that'd keep me awake rather than feel sleepy. I seem to have some form o

I always wondered why people would suggest "counting sheep" as it seemed like something that'd keep me awake rather than feel sleepy. I seem to have some form of aphantasia as I can only conjure up very disjointed and foggy images with no real details. So imagining not only one sheep but a number of sheep on a field jumping over a fence is something I can only just barely approximate with such considerable mental effort that it even makes me feel slightly anxious. This seems entirely unlike what the exercise apparently is meant to accomplish.