That seems like a bit of an assumption. Your body needs less O2 when sleeping and your respiratory rate slows as a result of that and many factors. I highly d

That seems like a bit of an assumption. Your body needs less O2 when sleeping and your respiratory rate slows as a result of that and many factors. I highly doubt someone sleeping next to you is materially taking away from the O2 you're breathing in. If so, you'd be fairly out of breath in a room full of people during the day. Unless the room you're sleeping in already has such low level of O2, you might need to look into a monitor or even using a fan to move some air.