Stress can impact ones ability to fall asleep and can disturb the natural sleep-wake cycle. Source Naturals Melatonin Serene Night addresses these two aspects of occasional sleeplessness. Melatonin is a neurohormone shown in research to promote a normal and healthy sleep-wake cycle and to help the body ease into sleep more quickly. L-Theanine is an amino acid that may help to reduce tension and promote relaxation, which then may help the body transition to sleep more easily. Melatonin Serene Night delivers amounts of melatonin and theanine.