Apple Watch Series 8 and Apple Watch Ultra support new wrist temperature sensing to provide users with insightful data on their overall well-being. In a new support document on the capability, the company details that Apple Watch Series 8 and Ultra require 5 days to establish users’ baseline temperature.
Powered by two temperature sensors, under the screen and display, the new Apple Watch Series 8 and Apple Watch Ultra sample users’ wrist temperature every five seconds while they sleep. Next, that data is used by advanced algorithms to provide an aggregate for each night which is recorded in the Health app for users to view as relative changes from the established baseline temperature.
Sleep tracking and Sleep Focus must be set on compatible Apple Watch for 5 nights to establish wrist temperature baseline
As detailed in the document, Apple Watch Series 8 and Ultra owners need to set up Sleep via Track Sleep and Sleep Focus for at least four hours every night for 5 nights to establish their wrist temperature baseline with a proper fit, not too loose.
It is explained that body temperature changes naturally and factors like diet, exercise, sleep, environment, and others can cause fluctuations in body temperature every night. Therefore, the latest high-end Apple Watches require 5 nights of sleep tracking to determine users’ baseline temperature.
Your wrist temperature is a measurement related to your body’s temperature taken by your Apple Watch while you’re asleep. Your body temperature naturally fluctuates and can vary each night due to your diet and exercise, alcohol consumption, sleep environment, or physiological factors such as menstrual cycles and illness.
After about 5 nights, your Apple Watch will determine your baseline wrist temperature and look for nightly changes to it.
Although the company highlighted that wrist temperature will be most useful for women to improve monitoring of their menstrual cycles and receive retrospective ovulation estimates for fertility planning, it will also be useful for alerting the user of possible cycle deviations such “as irregular, infrequent, or prolonged periods, and persistent spotting, which can be symptoms of underlying health conditions.”
Having said that, users must keep in mind that the wrist temperature sensing feature is for 14 years or older users, and it is not a medical device and should not be used for medical diagnosis, treatment, or other purposes.