Interpreting Oura Ring Biometrics: Part II — Sleep

Trevor Hess
Oct 30, 2020
10 min read

Updated: Nov 5, 2020

In part I of this two-part series, I talked all about the biometrics the Oura Ring has to offer when it comes to readiness. However, that's just the half of it; in fact, I'd say that sleep is the majority of it when it comes to taking advantage of the $300 ring you spent your hard-earned cash on.

So what is it? To recap a little, it is your ability to optimize your health by gaining the understanding to interpret your own Oura Ring biometrics, beyond just looking at your readiness and sleep scores each morning. Why is this important? Although the scores, which are measured out of a 100, are a great starting point for improving your health, I've experienced first-hand in the morning where both scores were high, yet I still didn't feel refreshed. So if you want to rather optimize your health, you need to learn how to interpret your data using both your scores and the individual biometrics themselves.

Now, the reason I feel the sleep section is more important than the readiness section is two-fold:

Some of the biometrics in the readiness section are also utilized by the sleep section.
I feel that the sleep biometrics have a greater impact on the outcome of the readiness biometrics than vice versa.

So without further ado, let's hop right into the sleep biometrics of the Oura Ring.

1. Resting Heart Rate

I figured I'd start off with resting heart rate (RHR) since I not only covered this in my previous article, but like I mentioned, both the readiness and sleep sections utilize this metric. Regardless, just like you want to see a general trend of decreasing RHR over time, you want to see the same trend occurring while you sleep.

Although it's almost guaranteed that RHR will decrease during the majority of the night due to body temperature naturally decreasing while you sleep, it's important to see how fast your RHR decreases as well. The reason behind this is whether you're stressed out or ate a large meal too close to bedtime, both demand more energy than being relaxed before falling asleep. As a result, if you find either of these events occurring, you can bet it's going to take a much longer time for your RHR to decrease and reach it's lowest point during the night.

Out of the two scenarios, I actually believe the single most important habit you can implement to improve your sleep is finishing your last meal of the day at least 3 hours prior to bedtime. In fact, the energy demand of metabolic processes is so high, that the calories you burn digesting your food accounts for a whopping 5-15% of your total energy expenditure per day. And you thought exercise burned a lot.

The other major point you want to pay attention to is how low your RHR gets during the night. Similar to how fast it takes your RHR to decrease, your minimum RHR during the night can be a great indicator for any poor habits from the previous day. In fact, I think your minimum RHR is an even better indicator for recovery. Why? Well, seeing how fast it takes for RHR to decrease is a great indicator for how you've wound down prior to bedtime. However, I think minimum RHR paints a better picture of the stresses from the prior whole day rather than just the evening. Whether you're overtraining, consumed caffeine, or consumed alcohol, you can bet that your minimum RHR is definitely going to be higher than usual, as these are all stresses your body has to manage. So to recap, when looking at your RHR as a sleep metric, you want to see your RHR decrease quickly during the night upon falling asleep and you want your minimum RHR to be as low as possible.

2. Sleep Efficiency

When looking at the dashboard for the sleep section in the Oura Ring app, you may notice there's three other biometrics besides RHR. Although, I do think total sleep time and time in bed are worth paying attention to, as long as your getting 7-9 hours of sleep or enough to feel well-rested, I personally think sleep efficiency is the only one worth keeping a closer eye on. Why? It's simple — both total sleep time and time in bed are used to calculate sleep efficiency.

Sleep efficiency is the percentage of time in bed spent asleep. As a result, you can simply divide total sleep time by time in bed, multiply that value by 100, and you've got yourself sleep efficieny. Like RHR, sleep efficiency can be extremely insightful, but instead of using this biometric to improve your habits during the day and prior to bedtime, I believe sleep efficiency is much more useful for analyzing how your sleep environment may be impacting your recovery.

There are a number of ways your sleep efficiency could be taking a toll, but the main reasons are usually that:

Your sleep environment is too hot. An optimal sleep environment temperature is between 60-69F. If there's too much argument in the household over sleep temperature since everyone's preferences are different, I recommend looking into an Ooler Sleep System.
Your sleep environment is too loud. Sometimes it's hard to craft a quiet sleep environment if you're living in a noisy neighborhood, or simply live with a noisy family. In this case, try using sleep earplugs.
Your sleep environment is not dark enough. Try eliminating blue light at least 2 hours before you go to bed by utilizing blue light blocking glasses since blue light can inhibit melatonin production, which is essential for sleep. Once you're ready to fall asleep, I recommend slipping off the glasses and popping on a comfortable sleep mask, since it's hard, especially with a other members in the house, to keep your room completely dark during the whole duration of the night.

Implementing all or some of these strategies is a sure fire way to reduce time awake while in bed, and is even extremely helpful for reducing tossing and turning throughout the night as well, which is another metric the Oura Ring tracks called "restfulness." I chose not to spend time discussing restfulness because as long as you focus on improving your sleep efficiency, restfulness should improve as well. So to recap, you should aim for as close to 100% sleep efficiency as possible every night.

3. Sleep Stage Durations

Finally, though these biometrics aren't the center-stage of the sleep section in the Oura Ring app, I find it extremely valuable to pay attention to the amount of time you spend in specific sleep stages. Like I said, I don't think total sleep time is all that important, and for good reason. Why? Well, there's a huge difference between the quality of sleep and the quantity of sleep you get each night. To explain this concept, I think it's best to address the science of sleep stages.

There are two main types of sleep that every human experiences throughout the night:

Rapid eye movement (REM) sleep
Non-rapid eye movement (NREM) sleep

REM sleep is also known as stage 4 (N4) sleep. Most people will experience about 4-5 periods of REM sleep per night, with the periods gradually getting longer as the night progresses. So why's this important? REM sleep is essential to cognitive functions including memory, learning, and creativity. So if you're not getting enough total sleep time each night, chances are, you're missing out on a ton of REM sleep since the end of a night of sleep is when you get it most.

NREM sleep can further be divided into three stages. Stage 1 (N1) is known as "drowsy" sleep and is the lightest sleep stage. Stage 2 (N2) occurs when the body enters a more subdued state, and this is the stage we usually spend most of our time in each night. Finally, and most importantly, is stage 3 (N3), also known as "deep sleep."

Deep sleep is one of the most, if not, the most important sleep stage to focus on logging each night. Why? Deep sleep is essential for bodily recovery and growth, as well as cognitive functions including insightful thinking, creativity, and memory. Since deep sleep acts as a sort of two-part approach to recovery, it's cearly essential for optimizing your health. Unlike REM sleep, the majority of your deep sleep occurs at the beginning of a night of sleep, with periods of deep sleep gradually becoming shorter as the night progresses.

Regardless, the typical percentages of time spent in each sleep stage are as followed:

Awake Time: 1-5%
REM Sleep (N4): 20-25%
Light Sleep (N1 + N2): 50-55%
Deep Sleep (N3): 15-20%

Obviously, these values aren't a one-size-fits-all. In fact, I believe that as long as you're getting a significant amount of deep sleep and some amount of REM sleep, you can almost guarantee you'll wake refreshed each morning. However, I've noticed the amount of deep sleep one gets is heavily correlated to stress put on the body during the day. As a result, the more you participate in exhaustive sports performance training or even exhaustive tasks that challenge your brain at school or at work, the more deep sleep your body will likely require each night . So to recap, it's best to focus on getting better quality sleep by improving your sleep environment so that you can log as much REM and deep sleep as possible.

What About Activity?

For those of you who have a good eye, you may have noticed I didn't include the activity section in my two-part series, and for good reason — I simply think it's not a good indicator for optimizing your health.

The Oura Ring's activity section primarily only measures the amount of steps you get each day, which is then used to calculate estimated walking distance and calories burned. However, at this point, I bet you're not surprised that I don't think the amount of steps you get each day is of much use, unless you know what you're doing with those steps each day.

To explain, in today's day and era, we simply don't walk as much as we should — period. Yet, we seem to think that our hour-long session at the gym makes up for it. This just isn't the case.

Humans were meant to move much more frequently, and it's shown that the more we stay active throughout the day, the better our health. One such factor that's drastically improved from being more active is our insulin sensitivity. When you're insulin sensitive, you're likely to be more metabolically healthy, and thus can handle fairly large intakes of carbohydrates no problem. However, when someone's insulin resistant, we begin to see the risk of developing diabetes, cardiovascular disease, and many other diseases increase substantially.

So what does this have to do with walking? Well, it's also known that the longer we sit during the day, the more insulin resistant we become as the day progresses. As a result, sitting for long durations causes our metabolism to go hay-wire and not know how to process glucose like it should.

You're probably thinking, "What can I do to walk more?" Some of the best strategies I've implemented include:

Going for a 15-minute walk first thing in the morning.
Utilizing a standing desk while at work, especially if working remotely.
"Greasing the groove" with mini-workouts every half-hour or so, such as by doing 20 kettlebell swings, pushups, or any other exercise that can get you breathing a little harder.
Going for a 15-minute postprandial walk after dinner.

Once you begin implementing these habits, you're on a sure-fire way towards getting all the steps you need for the day, which coincidentally, comes out to about the typical 10,000 steps per day everyones knows and loves… or hates.

So what about that hour-long session? I'm not advocating for you to quit working out. What I'm saying is that only relying on your workout session for all your movement during the day is not healthy. This is especially important given the fact that it can actually become quite dangerous to sit all day with "kinked" blood vessels, then jump right into a heavy weight lifting session with poor blood flow as a result of your sedentary habits. So to recap, don't obsess over the amount of steps you get each day, but rather focus on implementing frequent movement throughout the day with occasional intense activity.

What About Other Fitness Trackers?

I figured I'd address this question, as it's bound to come up anyway. Bottom line, I try to be as unbiased as possible. In fact, the Oura Ring isn't the first fitness tracker I've used, given that I've also tried the WHOOP, Biostrap, AppleWatch, and FitBit.

So what's the deal with them? I don't want to go too in-depth on each one, but for starters, I think the Biostrap, AppleWatch, and FitBit do have their place. However, I think the problems that arise with each include inefficient sampling time, EMFs (more on this in another article), and simply not enough biometrics, respectively. I especially prefer not to use an AppleWatch or FitBit given that they have screens, and I personally, prefer a more minimalist design.

Back to the WHOOP, I definitely think this device comes a close second to the Oura Ring, since both wearables practically utilize the same type of user interface, and since I do believe the WHOOP has a better activity tracking section.

However, I do still think the Oura Ring is a better choice. Reason being that for one, the WHOOP is subscription-based rather than a one-time payment. Second, it utilizes a green light for sensing rather than an infrared light like the Oura Ring uses, and like blue light, green light is known to disrupt sleep, even when applied to the skin since our skin also has photoreceptors like our eyes, And third, the WHOOP doesn't have an airplane mode setting like the Oura Ring, so it'll constantly bombard you with EMFs during the night, which is also known to disrupt sleep.

Summary

So there you have it, you now know how to actively interpret your Oura Ring data beyond just the readiness and sleep scores. Like I said, the more you interpret your data, the better you'll be able to understand your body as well as determine what habits are preventing you from optimizing your health. It's all a learning curve, so enjoy the process, and have fun becoming a better version of yourself each and every day!

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