STOPEATS is a first aid acronym that lists possible reasons for a casualty's decreased level of consciousness.
Sugar - hypo or hyperglycemia
Temperature - extreme temperatures and/or altered body temperature; hypo or hyperthermia
Oxygen - abnormal levels of oxygen can alter one's consciousness
Pressure - increasing ICP due to head trauma or a traumatic brain injury (TBI)
Electricity - trauma from electric shock or problems in the brain
Altitude - high altitudes can result in high altitude pulmonary edema (HAPE) or very low altitudes (i.e. underwater) can result in nitrogen narcosis
Toxins - drugs, alcohol, poisons, etc.
Salts - low sodium or potassium levels can alter the brain's conductivity