One of the biggest threats to a man’s heart after 40 doesn’t show up in the gym, the kitchen, or even at the doctor’s office.

This illustration photo shows an Apple Watch 9 displaying the blood-oxygen level detection settings, in Los Angeles on Dec. 26, 2023. Apple Inc. will begin selling versions of its Series 9 and Ultra 2 ...

Oxygen is critical to life. When levels of oxygen change, it can have immediate and lasting impacts on a person's health.