Sustained-release melatonin to support healthy sleep | Melatonin-SR provides sustained-release MicroActive melatonin to promote healthy sleep. Melatonin is a hormone produced by the pineal gland, which regulates the body capsules by Pure Encapsulations sleep/wake cycle. Melatonin capsules by Pure Encapsulations primary role is regulation of the body capsules by Pure Encapsulations circadian rhythm, endocrine secretions, and sleep patterns. Studies indicate that it facilitates the onset of sleep, as well as sleep efficiency. MicroActive is an innovative, patented delivery system that offers both improved absorption and sustained release. A pharmacokinetic study of MicroActive melatonin demonstrated rapid uptake and prolonged presence in plasma up to six hours after a single dose.