I'm an obese man and had severe sleep apnea. Last year I got a sleep study and started using a BiPAP machine from ResMed. The different was night and day (sorry). Huge improvements to my energy levels and ability to just function during the day.

One thing that was really interesting in this process was understanding the machine itself. Being used to crappy consumer electronics, I was amazed at how robust the build quality was and the engineering involved. Every little eventuality of medical accessibility problems, or things that could go wrong were accounted for in the design somewhere. It's incredibly simple to use, easy to clean, easy to get spare parts if needed. I guess that's the quality you get when your device costs upwards of $2,000.