Brown Out (as in “unconscious”)

Brown out as in “unconscious” is the dimming of vision caused by loss of blood pressure or hypoxia.  It is sometimes referred to as a grey-out. 

A brown out can be caused by any number of things however the most common causes are shock, standing up  too quickly, experiencing positive g-force, or, oddly enough, hyperventilation from such activities as the fainting game or self-induced hypocapnia.  

Full recovery from a brown out is rapid and can be reversed quickly and effectively by lying down.  This allows the cardiovascular system to allow blood to reach the brain.

Interestingly enough, brown outs are the reverse of red outs — reddening of the vision — which is the result of negative G forces.  During brown outs, individuals can still hear, feel and speak.

A brown out can also refer to a night of heavy alcohol consumption where the individual remembers some of what happened during the time alcohol was consumed but with periods of time within that time frame where there is no recollection of what happened.  This definition has been around since the early 1980s.

Even though it’s a lesser known expression, along with the expression black out, brown out has its roots in the 1940s.

See “black out” for additional information.