If I’m laying in bed for a long while unable to fall asleep, I’m I allowed to lay on my back or front to help me fall asleep?

One may lay down on his back, if the head and shoulders are elevated and are higher then the rest of the body.

Source:

עפ”י נשמת אברהם או”ח סי’ סג ס”ק א בשם הגרש”ז אויערבאך.