Giving Discomfort the Finger | Why the Oura Ring is a Ring

June 12, 2019

Have you ever wondered why the Oura ring is a ring? Why is it not the Oura Watch or Oura Earlobe Sensor Px4500? It’s time to find out.

There are two main reasons:

  • Wearing comfort
  • Signal quality

But first, let’s quickly go over the fundamentals. To build a solid sleep improvement solution, you need solid and accurate measurements of physiological changes in your body: such as heart rate and body temperature. The key question is: how can we get high-quality measurements while not disturbing sleep. Or in other words, how can we make something that’s useful but not cumbersome.

How comfortable are the options out there?

You can achieve our goal with different form factors, some of which have been around for decades (and some for thousands of years):

  • ring
  • wristwatch
  • wristband
  • headband
  • finger clip
  • earlobe clip
  • implants
  • mattress pads
  • self-adhesive electrodes

Intensive care units use finger clips for monitoring pulse. Athletes use sports watches, and sleep labs use self-adhesive electrodes. Some of the options on the list fulfill the first requirement (high-quality measurements) but fail on the second (not cumbersome). Let’s look at the list again:

  • ring: not for everyone
  • wristwatch: bulky
  • wristband: uncomfortable
  • headband: bothersome
  • finger clip: limits movement
  • earlobe clip: may cause discomfort
  • implants: invasive
  • mattress pads: comfortable but not portable
  • self-adhesive electrodes: uncomfortable and disposable

You can’t spell ‘wearing comfort’ without a ring. The Oura ring is designed to be worn around the clock, and especially at night. That’s reason number #1 it’s a ring.

How good is the signal?

It’s not wise to build a house on shaky grounds. If the signal you’re building on is off, your house will be a crooked mess of mixed metaphors. Good signal in, good insights out.

There are two main placements for optical heart rate sensors in wearables aimed at everyday users: the wrist and the finger. Both allow for free movement and can be used 24/7. Compared to some of the options out there, here’s how Oura stands out:

1. The Oura ring uses infrared LEDs

The infrared wavelengths of light go deeper into the tissue than, for example, green light. This allows the Oura ring to get the signal from the large arteries on the palm side of the finger, instead of the smaller capillaries at the surface of the skin.

Infrared light is invisible to the human eye

Infrared light isn’t affected as much by skin color or tattoos. Also, infrared light is invisible to the human eye so it doesn’t disturb you while you sleep.

Below you can see an example of the pulse waveform captured by the Oura ring. While you’re sleeping the ring captures the pulse waveform at 250 samples per second throughout the night. Good signal in, good insights out.

2. The Oura ring is designed for optimal fit

To get good data with optical heart rate measurement, there are some precautions to take:

  • the sensor shouldn’t move
  • the tissue next to the sensor shouldn’t move

In practice, this means that the measurement device needs to be strapped in tight. Some people find it uncomfortable to wear a heart-rate tracking watch as tightly as it should be, especially at night.

The Oura ring has the same requirements. However, because it’s a ring, it’s much more natural to find a size that is both snug and comfortable. The inner molding is non-allergenic so it’s comfortable to wear over longer periods, which is all good because the battery lasts 6–7 days.

Summary: the wrist, the finger or something else?

… is almost like asking cappuccino or avokado smoothie? If you want a watch, consider getting a watch. If you want a ring, perfect. But if you want a wearable designed especially for improving the quality of your life through better sleep, consider getting an Oura ring because that’s what it’s made for.

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