ARVO

A research study presented as a "poster" at ARVO 2010 indicated that the position of one's head (and body) during sleep can have an effect on intraocular pressure. For example, your eye pressure may be lower if you sleep on your back compared to sleeping on your side. (Furthermore, in my own experience, sleeping on your stomach may be the worst for IOP.)

Not discussed in this particular study was any difference in intraocular pressure between eyes. There is some evidence that if you sleep on your left side, intraocular pressure in the left eye could be higher.