Mothballs usually contain either dicholorobenzene or naphthalene to kill the moths. The second chemical is older and tends to cause more health problems. When swallowed, it kills red blood cells, which tires the body out and makes it weak and fatigued. Victims will be listless and unenergetic, and they may also show a lack of appetite. Restlessness often appears too; as tired as they seem, they may not be able to get any proper sleep.