[Image] “My child bought me a smartwatch that claims to measure blood oxygen levels while I sleep, but I found that the values it reports are higher than those from a medical pulse oximeter. How reliable are these results?” In the “Breathing Watch” discussion group, Ms. Zhao, a patient with COPD, raised a question that many friends are concerned about. Is the nighttime blood oxygen data monitored by smart devices reliable? When there are doubts about the device readings, can we observe our bodies to…