Sleep phaser positioning

i am not sure where to best position the sleep phaser, should it be on eye level or higher up? it only sometimes detects breathing rate and i think it does not detect rem phases at all, only light or deep sleep.

I used the instructions on Sleep Phaser docs with success. 45ยบ from the head towards the foot seems to work for me.

but which height is optimal? same as body or higher?

I am using it over a desk which is 30 cm above me (12 inches)