21st Century Melatonin 5 mg is a highly cost-effective option for melatonin supplementation, providing a commonly effective dose for initiating and maintaining sleep. The inclusion of 94mg of Calcium Carbonate is a minor addition, which might offer a very slight benefit for bone health or muscle relaxation, though its primary function is likely as a filler or binder. Its main appeal is its affordability, offering 120 servings at a very low price per serving. This makes it an excellent choice for consistent, long-term use without breaking the bank. While it doesn't offer a complex blend for multi-faceted sleep issues or stress relief, its simplicity and value make it a strong contender for basic melatonin needs.