Apple’s sleep charts can feel like a nightly report card, and “core sleep” often ends up in the spotlight. Yet the science behind wearables suggests that fixating on that one stage is a distraction ...

To see your sleep data, open the Health app on your iPhone and tap Browse, then Sleep. At the top of the screen, you will see ...

What is core sleep is on your Apple Watch, and does it even matter? We look at which sleep stages matter most for quality ...

Beth Skwarecki is Lifehacker’s Senior Health Editor, and holds certifications as a personal trainer and weightlifting coach. She has been writing about health for over 10 years. The Apple Watch has a ...