Plain-language health guides
Short guides to the numbers a smart ring reports, and what to do about them. Each one lists the pages we read and when we last checked them.
Pulse oximeters and blood oxygen: what is a normal oxygen level?
A pulse oximeter shows your oxygen saturation (SpO2). A normal oxygen level is 95% to 100% for most people. What a low reading means and why it can be off.
Resting heart rate by age, and what the numbers mean
A normal resting heart rate for most adults is 60 to 100 beats a minute. Ranges for children, what changes your pulse, and when to see a doctor.
What is heart rate variability, and should you track it?
HRV is the small change in time between heartbeats. What affects it, why there is no single normal number, and how to read your own trend.
Deep sleep: how much is enough, and can you trust your tracker's number?
Most adults spend 10% to 20% of the night in deep sleep, roughly 40 to 110 minutes. What changes it, and how far to trust a tracker's figure.
How to find your ring size before you order
Measure with string or paper at the end of the day, size between your knuckle and the base of the finger, and check the fit. US sizes 6 to 13 for Zenlyf.
Fall detection for older adults: what a fall detector can and cannot do
Fall detection for seniors can call for help after a fall, but research does not show it prevents falls. How fall alerts work, their limits, and what to ask.