It is critically important to ingest sufficient quantity of salt in a rainforest environment. Most people from a northern clime sweat profusely, as the body attempts to cool itself in the hot, humid environment. The level of sodium lost during sweating must be replenished or a condition of hyponatremia will ensue. Essentially, the plunging level of sodium in the blood drives fluid into the body's cells. In the cranium, the resulting swelling of the brain first leads to symptoms of dizziness and headaches, as well as mood swings. If untreated by the simple ingestion of salt, advanced symptoms include severe vomiting, coma and ultimately death.