Probably only at night when things are calm enough it activates that measurement...

manwe150 on May 30, 2023 | parent | context | favorite | on: Are you breathing? Do you have email apnea? (2014)

Probably only at night when things are calm enough it activates that measurement, or if blood oxygen levels drop for long enough. I am unsure whether the change in blood oxygen would be detectable though—has anyone seen that measured based just on holding one’s breath for varying lengths of time?

callalex on May 30, 2023 [–]

Apple watch only checks oxygen levels every hour or so, and only if you are completely still.