Key Takeaways
- Sleep trackers are reasonably accurate for total sleep time but less reliable for sleep stages
- For some people, tracking creates "orthosomnia"—anxiety about sleep scores that worsens actual sleep
- Trackers are best for spotting trends over time, not for judging individual nights
- How you feel matters more than what your tracker says—subjective experience is valid data
- Consider tracking temporarily to identify patterns, then stopping if it causes stress
Every morning, millions of people wake up and immediately check their wrists. Did I get enough deep sleep? What's my sleep score? But is all this data actually helping us sleep better—or making things worse?
I wore a sleep tracker religiously for two years. I have thoughts. Not all of them are positive.
01 How Sleep Trackers Work
Consumer sleep trackers use various technologies to estimate your sleep:
Accelerometer
Measures movement. More movement = assumed wakefulness. Less movement = assumed sleep. Simple but surprisingly effective for detecting when you're asleep.
Optical Heart Rate (PPG)
Uses light to detect blood flow and measure heart rate. Heart rate variability patterns help distinguish sleep stages (heart rate typically drops during deep sleep).
Oxygen Saturation
Some devices measure blood oxygen levels. Useful for detecting potential sleep apnea, though not diagnostic.
Temperature Sensors
Body temperature drops during sleep. Skin temperature patterns can help identify sleep onset and different sleep phases.
Tracker vs. Sleep Lab (Polysomnography)
Clinical sleep studies use EEG (brain waves), EOG (eye movement), and EMG (muscle activity) to definitively measure sleep stages. Consumer trackers infer this from movement and heart rate—a fundamentally different approach.
02 How Accurate Are They?
Accuracy varies significantly depending on what you're measuring:
"Consumer devices were moderately accurate for sleep/wake detection but performed poorly for sleep staging, particularly for deep sleep."
— Sleep Medicine Reviews, 2021
03 Real Benefits of Sleep Tracking
Awareness
Many people underestimate how little they sleep. Seeing actual data can be a wake-up call (pun intended) that motivates change.
Trend Detection
Weekly and monthly averages reveal patterns: maybe you sleep worse on Sundays, or better when you exercise. This is where trackers shine.
Consistency Accountability
Seeing your sleep/wake times can encourage regularity. The data shows when you're drifting from good habits.
Red Flag Detection
Unusual patterns (consistently low oxygen, extremely high heart rate during sleep) might prompt a conversation with your doctor.
04 The Downsides of Sleep Tracking
Morning Anxiety
Waking up to a "bad" sleep score can ruin your morning—even if you felt fine before checking. The data becomes a self-fulfilling prophecy.
False Precision
Trackers present data with false certainty. "You got 47 minutes of deep sleep" sounds precise but may be off by 30+ minutes.
Misaligned Goals
Optimizing for a "sleep score" isn't the same as optimizing for how you feel. These metrics are proxies, not the real goal.
Nocebo Effect
Believing you slept poorly (because the tracker says so) can make you feel tired— even if the tracker was wrong.
05 Orthosomnia: When Tracking Backfires
Researchers have identified a new condition: orthosomnia—a preoccupation with achieving perfect sleep data that actually worsens sleep[1].
Signs You Might Have Orthosomnia
- You feel anxious before checking your sleep data each morning
- A "bad" score ruins your mood for hours
- You feel tired after a night your tracker rated as poor—but felt fine before checking
- You've changed good habits to chase tracker metrics
- You check your tracker multiple times during the night
The irony is painful: the very tool meant to improve sleep can become a source of the performance anxiety that prevents it. If this sounds familiar, it might be time to take a break from tracking.
06 Who Should (and Shouldn't) Track
Tracking May Help If You:
- Are curious about your sleep patterns and won't obsess
- Want to identify how behaviors (alcohol, exercise) affect sleep
- Need accountability for consistent sleep schedules
- Are motivated by data without being anxious about it
- Use it temporarily to establish baselines
Consider Skipping If You:
- Already have sleep anxiety
- Tend to obsess over health metrics
- Notice your mood depends on your sleep score
- Feel worse after checking data than before
- Have a history of perfectionism
The Golden Rule
If the tracker is making you sleep worse, stop using it. No data is worth sacrificing actual sleep quality. Your subjective experience of feeling rested is valid—perhaps more valid than any algorithm.
The Bottom Line
Sleep trackers are tools, not oracles. They're reasonably good at tracking total sleep time and spotting trends, but their sleep stage data should be taken with a grain of salt.
For some people, trackers provide valuable insights and motivation. For others, they create anxiety that makes sleep worse. There's no shame in either experience.
The ultimate measure of sleep quality isn't a score or percentage—it's how you feel when you wake up and function throughout the day. If your tracker says you slept terribly but you feel great, trust your body.
Sources & Further Reading
- "Orthosomnia: Are Some Patients Taking the Quantified Self Too Far?" Journal of Clinical Sleep Medicine, 13(2), 351-354. (2017) PubMed →
