Spring Valley 5-HTP Mood Health / Sleep Support Capsules 100 mg 30 Capsules.Spring Valley 5-HTP 100mg Capsules (short for L-5-Hydroxytryptophan) provides nutritional support to help your brain produce serotonin. Serotonin acts as a chemical messenger in your body, contributing to ...Spring Valley 5-HTP Mood Health / Sleep Support Capsules 100 mg 30 Capsules.Spring Valley 5-HTP 100mg Capsules (short for L-5-Hydroxytryptophan) provides nutritional support to help your brain produce serotonin. Serotonin acts as a chemical messenger in your body, contributing to a calm, relaxed mood and a positive emotional outlook.