This isn't specifically sleep study related but my dad, who has undergone a sleep study and was diagnosed with sleep apnea, takes magnesium supplements and says they help him sleep wonderfully. I've tried taking them as well and they definitely knock me out. If you're looking for something natural to try I'd suggest checking out Natural Calm Magnesium

Best of luck to you! I hope you start getting more sleep soon, no matter what route you end up taking.