Oura Ring Gen 4: Six Months of Sleeping With a Computer on My Finger

The Pitch vs. The Reality

Oura will tell you their ring is the gold standard of consumer sleep tracking. They have research partnerships, peer-reviewed validation studies, and celebrity endorsements. The Gen 4 improved the sensor array over Gen 3, adding two additional red and infrared LEDs for better signal quality and a new peripheral arterial tonometry algorithm.

I wore it for six months. Here’s what held up and what didn’t.

What Oura Gets Right

HRV measurement. This is the ring’s strongest feature. Heart rate variability — the variation in time between heartbeats — is one of the best proxies we have for recovery status and autonomic nervous system health. Oura measures HRV during your lowest resting period of the night, which research suggests is more meaningful than morning or daytime measurements. Over six months, my HRV data correlated reliably with how recovered I actually felt, and with objective stressors I could identify in retrospect.

Resting heart rate. Accurate, consistent, and genuinely useful. When I was coming down with something, my resting HR elevated 3–4 BPM before I felt any symptoms on three separate occasions. This alone is worth something.

Temperature deviation tracking. The Gen 4’s temperature sensor picks up the 0.1–0.2°C nighttime fluctuations that correlate with illness onset, ovulation timing, and recovery stress. For cycle tracking specifically, this is more sensitive than most dedicated BBT thermometers.

Form factor. It’s a ring. You forget it’s there. After a week I stopped noticing it entirely, which is not something I can say about any wrist-based wearable I’ve tested.

Where It Struggles

Sleep staging accuracy. This is the number that gets the most attention and it’s the least reliable. Consumer wearables cannot do what a polysomnography (PSG) lab test does — they don’t have EEG data. Oura estimates sleep stages using movement, heart rate patterns, and temperature. Compared to my PSG results, Oura overestimated deep sleep by 22% and underestimated light sleep. REM was within reasonable range.

This matters because a lot of people are optimising their sleep based on the staging data — timing supplements, adjusting sleep schedules, worrying about insufficient deep sleep. If the staging data is off by 20–25%, those optimisations may be built on shaky ground.

The Readiness Score gamification problem. The readiness score aggregates your HRV, resting HR, temperature, sleep, and activity data into a single number between 1 and 100. In theory, useful. In practice, I found myself making decisions based on it rather than how I actually felt — and occasionally overriding genuine fatigue because the score was high, or skipping a planned workout because the score was low.

The score is a compression of already-imperfect data. Treat it as one input, not an authority.

Battery and subscription. Six days of battery life is good for a ring. But the $5.99/month membership required to access most insights is a recurring cost that deserves honest accounting. The ring costs ~$350–$500 upfront. The subscription adds $72/year. Over three years, that’s $500–$700 total.

How It Compares to WHOOP

I’ve worn both. The core difference: WHOOP is built around strain and recovery for athletic performance; Oura is built around sleep and readiness for general health. WHOOP’s strain model is more sophisticated for training load management. Oura’s sleep data is more detailed and its form factor is dramatically more comfortable for sleep.

For people whose primary interest is sleep quality and daily recovery, not workout optimisation, Oura wins. For serious athletes tracking training load, WHOOP’s coach-facing features are more developed.

The Verdict

After six months, I’m still wearing it. That’s probably the most honest endorsement I can give — I’ve tested enough wearables to know which ones end up in a drawer.

The HRV trend data, resting HR, and temperature tracking are genuinely valuable and hard to get from less expensive devices. The sleep staging accuracy limitations are real but don’t invalidate the device — you just have to understand what you’re looking at.

If you’re going to buy one, buy it for the trend data over weeks and months, not for nightly staging accuracy. The signal is in the trajectory, not any single night’s numbers.

Rating: 7.5/10 — exceptional HRV and temperature tracking undermined slightly by overstated sleep staging precision and a subscription model that feels extractive given the hardware cost.