The story of a doctor who almost fell asleep during an outpatient visit on a day with a sleep score of 95

On the morning my Oura Ring sleep score was 95, I headed to the outpatient clinic feeling pretty good.

I went to bed at 10 PM last night. I got plenty of deep sleep. My HRV was high. The app displayed 'Optimal'.

However, I was incredibly sleepy during my morning outpatient clinic.

It wasn't that I actually fell asleep. But while listening to patients, there were several moments where I realized, 'Oh, my concentration is gone.' I noticed myself zoning out while typing up medical records and stood up to get some coffee.

Even with a 95, this?
For three years, I had looked at my score every day, convinced that 'a high score means a good day,' but everything fell apart on this day.

Data doesn't determine your physical condition. Your physical condition is just reflected in the data.

The order was reversed. I don't think this is just about me. For those who check their sleep scores on their smartwatches every morning, I want to write today about 'how to relate to numbers'.

Things I messed up with my smartwatch

Besides the incident where I almost fell asleep with a score of 95, there are a few other embarrassing stories.

The first thing I looked at when I woke up in the morning wasn't my wife's face, but my sleep score. If the score was 80 or higher, I was in a good mood. If it was 70 or lower, I was grumpy from the morning. My wife told me, 'Stop letting numbers change your mood.' I couldn't argue with that.

I was checking my heart rate on my Apple Watch while taking a bath with my son.
'Daddy, you're looking at your watch again.'
'I'm just seeing how much my heart rate goes up with the water temperature.'
Wife: 'Take that watch off.'
I took it off. I reflected on my behavior.

I glanced at my wrist while my wife was talking to me seriously.
'Which is more important, me or your heart rate variability?' I turned the watch over.
That's when I realized. I thought I was looking at data, but I wasn't looking at the person in front of me.

To begin with, how accurate is smartwatch sleep data?

For most people, smartwatch data is 'looked at too much.'

Heart rate. HRV. Blood oxygen levels. Sleep stages. None of these are medical devices. Whether it's an Apple Watch or an Oura Ring, only a very small fraction of their functions are certified as medical devices. Sleep scores and HRV are nothing more than 'reference values'.

In 2024, a research team at Brigham and Women's Hospital (a teaching hospital of Harvard Medical School) compared the sleep stage accuracy of the Oura Ring, Apple Watch, and Fitbit against medical-grade polysomnography (PSG) in 35 healthy individuals aged 20-50¹⁾.

Even with the Oura Ring, which had the highest accuracy, the detection sensitivity for sleep stages was 76–79.5%.

However, this 76–79.5% refers to the detailed classification of stages like deep sleep, light sleep, and REM. In fact, this stage classification is difficult even for medical-grade EEG examinations. Even if two expert technicians judge the same night separately, their assessments will not match perfectly. Since even human experts disagree, it feels harsh to blame the device for being off.

If it's a simple judgment of 'asleep or awake,' even in this study, all devices had a sensitivity of over 95%.

In other words, what smartwatches are bad at is the detailed stage classification,
at a level of 'it's mostly correct, but the stage classification is off once in every five times.'
If you ask me if the accuracy is worth getting happy or sad about every morning, I'd say, 'Hmm.'

There is even more concerning data.
There is a 2025 study by Schyvens et al. at the University of Antwerp that validated six types of wearables²⁾. The subjects were 62 people (average age 46) measured overnight in a sleep laboratory, and more than half were people who came for testing due to suspected sleep apnea. In this study, the detection sensitivity for 'asleep' was over 90% for all devices. Looking only at this, they look excellent.

But the detection specificity for 'awake' was 29–52%. Depending on the model, it misses 70% of wakefulness. Even though you are actually awake, the device judges that 'you are sleeping.'
No wonder the sleep score comes out high. It's counting time you aren't sleeping as time you are. I think my '95 but sleepy' experience was exactly this.

Becoming unable to sleep while chasing the perfect score (Orthosomnia)

In sleep medicine, there is a term called 'orthosomnia.' It is a condition reported by sleep researcher Baron and colleagues at Rush University in 2017³⁾.

It is the state of becoming unable to sleep because you are chasing a perfect sleep score.

Low sleep score → feeling anxious → can't sleep → score drops. An infinite loop.

A paper by Baron et al. reports on three patient cases. What they had in common was changing their behavior to match the tracker's data. All three stayed in bed longer, trying to increase the sleep time displayed by the tracker. The authors write that this may have actually worsened their insomnia.

What's even more troublesome is the case where, even after performing an EEG at the hospital and telling them, 'You are sleeping just fine,' they believe the tracker instead, saying, 'But the tracker says I'm not sleeping.' They trust their smartwatch more than medical equipment.

It's not a laughing matter; my own 'getting grumpy when it's below 70' was exactly the beginning of this.

This is a bit of a tangent, but I see several patients in the outpatient clinic who are similar to this. They ask with a serious face, 'Doctor, my score is in the 60s, is that okay?' When I listen closely, they are perfectly fine during the day. Their physical condition is being dictated by numbers.

Numbers you should look at vs. numbers you don't need to look at (how to use wearable data)

After recording smartwatch data every day for three years, this is how I use it now.

Things you don't need to look at every day:
Sleep score. Daily calories burned. Blood oxygen levels. Heart rate variability per beat. Step count. All of these just make you worry, and they don't change how you move that day.

Things that are meaningful when viewed on a weekly basis:
Resting heart rate trends. Weekly average HRV. Average sleep duration.
Are they going up or down? You only need to look at the direction. Don't worry about the absolute value of the numbers. Just whether it's higher or lower than last week, that's all.

If your resting heart rate is up by 3 bpm or more on a weekly average, be careful.
It's a sign of overtraining or poor physical condition. In my case, it's usually in the low 50s, and when it exceeds 60, it's usually a sign of a cold.

The weekly average of HRV should only be compared with your own past data.
Individual differences are too large, so comparing it with others is meaningless.
If there is a downward trend for two consecutive weeks or more, it's time to increase your rest.

The truly important numbers are not on a smartwatch.
Blood pressure. HbA1c. LDL cholesterol. Uric acid levels. These can only be obtained through an annual health checkup. But these are more directly linked to your life.

I wrote about test items that cannot be seen in a 'no abnormalities' health checkup (fasting insulin, ApoB, high-sensitivity CRP, etc.) in The blind spot of an all-A grade. Vascular risks that cannot be seen in a health checkup. It is more effective to have these checked properly once a year than to look at your smartwatch every day.

I think there are quite a few people who look at their smartwatch every day but don't get a health checkup, but the priority of what to look at is reversed.

Don't look at the data. Look at your body.

So, what should you look at instead of a smartwatch? I will write down the self-check I do every morning.

Morning self-check (no smartwatch required):

1. Did you wake up naturally when you woke up?
If you woke up before the alarm went off, that alone is enough sleep.

2. Does your body feel heavy when you get up?
If you feel sluggish for no reason, you aren't getting enough rest, no matter what your sleep score is.

3. How is your concentration in the morning?
If you find yourself zoning out frequently by around 10 AM, your sleep quality has dropped.

That's all there is to it. I don't look at the numbers at all.
Over the past three years, I've learned that my own senses are often more reliable than a device's algorithm.

Waking up in the morning feeling somewhat sluggish—that is more accurate information than a sleep score.
Feeling sleepy after a meal—that is a sign of a blood sugar spike. It won't show up on a smartwatch. I wrote about how my blood sugar was clearly erratic after sleep deprivation or late-night meals when I tracked it for two weeks using a CGM in“The Surprising Truth About Blood Sugar I Discovered After Wearing a Libre”.

Joint pain during strength training—that is a more important warning than HRV. No matter how good your HRV is, if your joints hurt, you should reduce the load.

The signals your own body sends can sometimes be more accurate than any device.

I'm not saying smartwatches are bad. I still wear one myself. But the first thing I look at when I wake up in the morning isn't my sleep score, but the face of my son sleeping next to me.

One thing to do today

Turn off sleep score notifications on your smartwatch.

For Apple Watch: Go to the Watch App, select "Sleep," and turn off "Notifications."
For Oura Ring: In the app, go to "Settings" -> "Notifications" -> turn off "Sleep Summary."

I'd like you to look back at how you feel after one week. If you feel better on the days you didn't look at your score, that might be your answer.

Summary

• The detection sensitivity for sleep stages, even for the Oura Ring which was the most consistent, is 76–79.5% (compared to medical PSG). For Apple Watch, it drops to 50.5% for deep sleep.
  Orthosomnia = A state of becoming insomniac due to an obsession with perfecting wearable sleep data.

• Don't check daily: Sleep score, calories, blood oxygen, step count. Only look at the trends on a weekly basis.

• Three morning self-checks (natural awakening, body heaviness, morning focus). It took me three years to start looking at these before the numbers.

Thank you for reading this far.
If you found this helpful, giving it a "Like" would be a huge encouragement.I post about health topics I've tested on my own body, focusing on sleep and exercise, about once every few days.
I would be happy if you followed me.

For those who want to know more (Related Articles)

I have selected two articles to read after you stop looking at your scores. One is about setting up your environment, and the other is about grading yourself based on your own senses.

▼ Before the numbers, set the foundation(Free)
5 things you should do before sleep supplements
Room temperature, bathing, blue light, caffeine, and wake-up time. This is about setting up your physical environment and habits before looking at your smartwatch.

▼ Ditch the numbers and use my 5-question self-check(Free)
The "5-Question Self-Check" created by a doctor who fell asleep during an outpatient visit with a sleep score of 95
A sister article that further details the "morning self-check" from this article. It consists of 5 questions to assess your sleep in 30 seconds.

Announcement of the membership "Dr. Mosari Lab"
I run a membership called "Dr. Mosari Lab." I write about more in-depth topics that I cannot share on X or in free notes.

• Content I actually discuss in outpatient visits as a primary care physician for business executives

• Records of what worked and what didn't, tested on my own body while reading research papers

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*This article is intended to provide general health and medical information and does not constitute diagnosis, treatment, or medical advice for any specific individual. If you have health concerns, please be sure to consult a medical institution. The author assumes no responsibility for the consequences of actions taken based on the information in this article.

References

1. Robbins R, et al. Accuracy of Three Commercial Wearable Devices for Sleep Tracking in Healthy Adults. Sensors. 2024;24(20):6532.

2. Schyvens AM, et al. A performance validation of six commercial wrist-worn wearable sleep-tracking devices for sleep stage scoring compared to polysomnography. SLEEP Advances. 2025;6(2):zpaf021.

3. Baron KG, et al. Orthosomnia: Are Some Patients Taking the Quantified Self Too Far? J Clin Sleep Med. 2017;13(2):351-354.