Plain melatonin products contain only melatonin. Swanson Sleep Essentials contains the same 3 mg melatonin but also adds several components that are traditionally included in evening herbal formulas: valerian root, passionflower, chamomile, skullcap, hops, GABA and L-taurine. The idea is to support a more settled transition toward rest, rather than relying on melatonin alone.
The herbs in this formula are not presented in the product description as knockout sedatives. They are described as botanicals that help create a calmer pre-sleep atmosphere. GABA is a neurotransmitter involved in inhibitory signalling, the type of signalling linked with mental slowing-down. Taurine is an amino acid included in evening complexes for its role in the nervous system and balanced nerve signalling. Together, they give the formula a broader evening focus than a single-ingredient melatonin capsule.
If you already take a separate melatonin product, note that this capsule already provides 3 mg of melatonin. Using another melatonin product at the same time would mean doubling the amount; a safer route is to choose one source and stick with it. A pharmacist or doctor can help you decide on an amount that fits your usual routine.