Terra Research

New Year Resolutions Cliff

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

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

New Year Resolutions Cliff

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

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

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

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

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

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

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

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

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

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

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

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

Meet the Research Team

A team of scientists, engineers, and athletes working to make sense of the world’s health data.

Alistair Brownlee

Head of Research

Alistair Brownlee is Head of Research, where he leads large-scale analysis of wearable health data to better understand sleep, recovery and human performance, translating these insights into products that help people live healthier lives.

Faraaz Akhtar

AI and Health Researcher

Faraaz Akhtar is an AI & Health Researcher at Terra API, where he develops statistical and machine-learning methods to extract insights from large-scale wearable health data.

Rocio Mexia Diaz

AI and Health Researcher

Rocio Mexia is a Biomedical Engineer and AI & Health Researcher at Terra API, where she applies machine learning to wearable and health record data to uncover insights about human health.

Halvard Ramstad

Cameron Crawford