Vita Calm PMCompare to Ortho Molecular Cerenity PM Sleep is the bodys way of metabolically and psychologically resetting itself. The bodys circadian rhythm is regulated by an internal biological clock with an approximate 24 hour cycle. In order to maintain restorative sleep, it is crucial that the brain has optimal levels of serotonin and gamma aminobutyric acid (GABA), the relaxing and sleep regulating neurotransmitters, as well as the sleep regulating hormone