How long does the Purest light stay on? January 23, 2019 19:03 Updated The Purest control lights stay illuminated for only 4 seconds. The amber color of the light is designed to minimally disrupt your now perfect sleeping environment. Related articles My Purest Sleep Scent Diffuser is leaking water when running. What do I do? Does the Purest Sleep Diffuser have a white noise option? Are the Sleep Scents safe for use with toddlers and children? What is “pink noise”? Which product is loudest?