Women's Health
Why Readiness Scores Misread Women's Capacity
We analyzed ~3 million nights of Oura sleep data to see whether the menstrual cycle leaves a measurable signature in nig...
January 29, 2026
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All research articles
Here you can find all articles published by the Terra Research team. All articles consist of original findings.
Sleep Tracking
Sleep Metric Variation Across Wearables
We analyzed sleep data from 77,000+ nights across six major wearables, then zoomed in on same-person, same-night overlap...
January 22, 2026
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New Year Resolutions Cliff
The January Activity Spike: A two-day Story
We analysed wearable data from over 3,000 users to measure the New Year's resolution effect on physical activity. The re...
January 15, 2026
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Sleep Tracking
Sleep Patterns Across the World
We analyzed 8,298 sleep records from October 2025 across wearable users in North America, Europe, and beyond, linking ex...
January 6, 2026
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New Year Resolutions Cliff
New Year’s Resolutions Cliff
Every January, millions pledge to sleep more along with their New Year's Resolutions. But does it work? Analyzing more t...
December 31, 2025
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Sleep Tracking
How HRV Actually Works
We unpack what HRV really is and how it actually works to demystify the data from Oura, Apple Watch, Fitbit, and Garmin....
December 17, 2025
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Sleep Tracking
How Do People Really Use Wearables?
We analyzed 93 days of continuous sleep data across Oura, Fitbit, Apple Watch, and Garmin users to answer a simple quest...
December 9, 2025
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Sleep Tracking
Benchmarking Wearable Sleep Data Reliability
We analyzed sleep data from over 5,000 real-world nights across Oura, Apple Watch, Fitbit, and Garmin users. Garmin deli...
November 28, 2025
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Oura Ring Series
Is Consistency Actually More Important Than Intensity?
In this report, we reveal why high-step users averaging 11,500+ daily steps succeed: consistency. Their 36% activity var...
October 23, 2025
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Oura Ring Series
Which activity metrics actually matter? 28,000+ days analysed
Smart rings track five different activity metrics, but they don't always align. Drawing on nearly 28,000 days of user da...
October 9, 2025
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Oura Ring Series
Burn More Calories, Sleep Like a Log?
An analysis of 1,000+ Oura ring users examined the relationship between daily calorie expenditure and sleep metrics. Act...
October 2, 2025
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Oura Ring Series
GAMM analysis – can complexity tell us anything we don’t already know?
Based on an analysis of nearly 90,000 nights, the connection between sleep duration and next-morning HRV is minimal for...
September 25, 2025
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Oura Ring Series
Think a good HRV score follows a good night’s sleep? Think again!
Despite their perceived link, sleep and HRV are only weakly correlated. The analysis of nearly 90,000 nights showed that...
September 20, 2025
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Oura Ring Series
Descriptive HRV using Z scores
Based on an analysis of nearly 100,000 HRV records, this report reveals that most daily HRV changes are small, but large...
September 19, 2025
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Oura Ring Series
Why Mondays Might Be Your Healthiest Day: What 1,000+ Sleepers Taught Us About Recovery
At Terra, we recently ran an analysis on wearable data from over a thousand (Oura) users, focusing on two key metrics: s...
September 18, 2025
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