>>287426009
>Just about the only position you can sleep in a headset seems to be flat on your back

You can sleep on your side. Use one of those travel pillows that goes around your neck, only don't put it around your neck, lay it on its side so it's like a "C". When you lay down, your headset's earphones will be in the middle of the C and the headset itself will be in the open part of the C.

Source: Slept in vr every night for two years