ONU Journal: Preventive Health Articles

The knowledge collection

A good place
to begin.

Heart Rate Variability: What HRV Means & How to Use It

Learn what heart rate variability measures, why your baseline matters, what can change HRV, and how to interpret a low reading without chasing a score.

A sleep mask, bedside clock and diary on blue linen.

FIELD NOTES · 02

Sleep Scores Explained: Accuracy, Meaning & Limits

Understand how sleep scores are estimated, why a good score may not match how you feel, and how to use wearable sleep trends more effectively.

Gloved hands arranging capped sample tubes in a laboratory.

FIELD NOTES · 03

How to Read Blood Test Results: Ranges, Units & Flags

Learn how to read a blood test report, understand reference ranges and abnormal flags, compare results, and prepare useful questions for your clinician.

Morning light falling across an hourglass and fern.

FIELD NOTES · 04

Cortisol Explained: Symptoms, Testing & Stress Myths

Understand what cortisol does, why symptoms alone cannot diagnose high cortisol, how testing works, and what wearable stress scores can really tell you.

An adult resting at a kitchen table in afternoon light.

FIELD NOTES · 05

Always Tired? Understanding Fatigue & Low Energy

Explore persistent fatigue, how it differs from sleepiness, what to record, and when a healthcare review is more useful than another wearable score.

A closed laptop and glasses set aside at the end of a workday.

FIELD NOTES · 06

Burnout & Chronic Stress: Signs, Differences & Support

Understand burnout as a work-related phenomenon, how it differs from everyday stress, and practical ways to seek support and address ongoing demands.

Two generations walking together through an olive grove.

FIELD NOTES · 07

Biological Age Tests: Meaning, Limits & Healthy Aging

Understand what biological age estimates measure, why different tests disagree, and how to focus on useful preventive health decisions.

A clinician listening during a routine health check.

FIELD NOTES · 08

Preventive Checkups: What to Discuss & How to Prepare

Prepare for a preventive health visit with a clear history, medication list, screening questions and a follow-up plan tailored to your circumstances.

An unbranded supplement bottle beside almonds and water.

FIELD NOTES · 09

Supplements: Evidence, Labels, Interactions & Safer Choices

Learn how to assess supplement claims, read doses and ingredients, check interactions, and decide when testing or professional advice is more useful.

A walker pausing quietly on a park bench.

FIELD NOTES · 10

Resting Heart Rate Higher? Causes & Next Steps

Understand a rise in resting heart rate, check measurement conditions, recognize symptoms that need care, and compare trends without self-diagnosing.

An adult sitting on the edge of a bed in morning light.

FIELD NOTES · 11

Tired After 8 Hours of Sleep? Causes & Next Steps

Still tired after eight hours of sleep? Understand sleep quality, common causes of daytime fatigue, what to track, and when to seek medical advice.

A wave washing around a smooth stone on wet sand.

FIELD NOTES · 12

Acute vs Chronic Stress: Differences & Next Steps

How is acute stress different from chronic stress? Compare duration, common signs, what to track, and when ongoing stress calls for support.

Explore practical details

A CLOSER LOOK

ONU Journal: the essentials.

What matters, what to check, and where to go from here.

01
An editorial collection with a practical purpose
The ONU Journal explains common questions about wearable measurements, sleep, fatigue, stress, laboratory results and preventive decisions. The articles are educational and intended to help you understand limitations and prepare useful questions. They do not promise a diagnosis or a personalized treatment plan.
02
Use the collection by topic
Filter or search for the question that brought you here. If you are tired despite a full night, start with the eight-hours article and fatigue guide; if a report is confusing, use the blood-results article; if you are comparing recovery readings, begin with the HRV explanation.
03
Read beyond the headline
Check the direct answer, practical sections and sources before drawing a conclusion. Sources and update dates are visible so you can distinguish the explanation from an unsupported product claim.