Sodium deficiency, also known as hyponatremia, occurs when the sodium levels in the blood drop below normal. Sodium is an essential electrolyte that helps regulate fluid balance, nerve function, and muscle contractions. Low sodium levels can result from excessive sweating, certain medications, or medical conditions that affect fluid balance. Symptoms of sodium deficiency may include headache, confusion, fatigue, and muscle cramps. In severe cases, it can lead to seizures or coma. Maintaining a balanced diet that includes sources of sodium, such as table salt and processed foods, is important for overall health and proper bodily function.