Falling over, room spinning, feeling dizzy - too much alcohol really throws you off balance. But why?
To maintain our balance, we have fluid in our ears called endolymph. Suspended in this endolymph is a structure called the capula, which is covered in tiny little hairs named cilia. When we tilt our head, the fluid in the ears moves, which bends the tiny hairs on the capula. This sends signals to the brain telling us where our head is in space, and how (if necessary) to change our posture in order to maintain balance and stay stood up.
When we drink alcohol, the endolymph in our ears gets thinner and ‘runny’. This changes the shape of the capula, and bends the tiny hairs on its surface. This sends false, over-exaggerated signals to our brain about the position and movement of the head and this is what causes us to lose our balance, or even make us feel like the room is spinning when we are laying down.