Sleep Tracking – 4 Insights to Improve Your Sleep
Sleep tracking provides objective insights into crucial metrics like sleep stages, duration, quality, and schedule, helping identify detrimental habits that deteriorate sleep. By monitoring sleep data, users can make informed adjustments to improve their sleep score, supporting mental and physical recovery.
What is Sleep Tracking?
Sleep tracking is the process of monitoring and analyzing metrics associated with sleep. It provides insight into sleep schedule, depth, duration, compiling more metrics to grade overall sleep quality.
Wearable devices like rings, smartwatch, or smart mattress are typically used to assess one’s sleep performance. Based on the feedback, one can use the data to improve specific habits like stimulant use, bedtime, or blue light exposure that impair sleep.
Monitoring sleep is objective, tracking physiological metrics like breathing rate, sweating, sound, or movement. This makes it superior to subjective assessment of sleep quality which is less accurate. Seeing how changing specific habits changes sleep quality is motivating, accurate, and makes distinguishing bad habits easier.
The goal of sleep tracking is to improve the overall sleep score by shifting our sleeping habits to ones that favor higher scores. Quality sleep is essential for longevity, and optimal mental and physical performance daily.
Is sleep tracking good for you?
Yes, sleep tracking is beneficial as it provides insights into your sleep patterns, helping identify issues like insufficient deep or REM sleep, irregular schedules, or frequent awakenings. By analyzing this data, users can make informed decisions to improve their sleep habits, which is essential for overall health, cognitive function, and recovery.
Why is sleep monitoring important?
Sleep monitoring is important because it helps detect sleep disorders, assess sleep quality, and identify patterns that may negatively impact health. By understanding metrics like sleep stages, duration, and consistency, users can make targeted changes to enhance sleep.
How does a sleep tracker work?
Sleep trackers use sensors to monitor physiological signals such as movement (via accelerometers), heart rate (via PPG sensors), and sometimes even skin temperature or noise levels. Algorithms process these signals to estimate sleep stages, duration, and disturbances, providing a comprehensive analysis of sleep quality and patterns.
The 4 Sleep Phases
Sleep architecture refers to the structure of sleep, defined by sleep stages and their distribution throughout the night. It is a key factor in assessing sleep quality.
Using electroencephalogram (EEG) technology, scientists measure brain-wave activity to differentiate between wakefulness and sleep, which is categorized into two primary phases: non-REM (NREM) and REM (rapid eye movement) sleep. (1) (2) (3)
Non-REM Sleep
Non-REM sleep is divided into three distinct stages
- NREM Stage 1: The lightest sleep stage, lasting 1–5 minutes, and accounting for ~5% of total sleep. It marks the transition from wakefulness to sleep, with brain activity shifting from alpha to theta waves (4–7 Hz).
- NREM Stage 2: The most prolonged stage, comprising ~50% of total sleep. Body temperature drops, muscles relax, and EEG readings show sleep spindles and K-complexes, critical for memory consolidation. Each subsequent N2 cycle lengthens beyond 25 minutes.
- NREM Stage 3: This is the deep sleep stage, essential for physical recovery and growth, with the slowest brain activity at around 2-4 Hz (delta waves).
REM Sleep
The REM phase occurs approximately 90 minutes after sleep begins, initially lasting 10 minutes and extending with each cycle. This phase is characterized by vivid dreams, rapid eye movement, increased diaphragmatic breathing, muscle atonia, and occasional muscle twitches. REM plays a crucial role in emotional regulation and cognitive processing.
The duration of each sleep stage changes throughout the night. Early in the night, the Non-REM 3 or deep sleep stage dominates, slowly shrinking towards the morning. As the night advances, NREM Stage 2 becomes more prominent, and REM stages lengthen, supporting emotional processing and memory consolidation.
This cyclical interplay between NREM and REM stages forms the foundation of restorative sleep.
What are the 4 phases of sleep?
The four phases of sleep include
- REM Sleep: Associated with vivid dreaming, memory consolidation, and emotional processing.
- NREM Stage 1: Light sleep as the body begins to relax.
- NREM Stage 2: Deeper relaxation, characterized by reduced heart rate and body temperature.
- NREM Stage 3 (Deep Sleep): Crucial for physical recovery and growth.
Which is better, REM or deep sleep?
Both are equally important but serve different purposes. Deep sleep supports physical recovery, immune function, and growth, while REM sleep is essential for cognitive processes like memory, learning, and emotional regulation. A balanced amount of each is necessary for optimal health.
Are sleep cycles 90 minutes?
Sleep cycles typically last 90 minutes on average but can range between 70 and 120 minutes depending on individual variability, age, and health. Each cycle progresses through light sleep, deep sleep, and REM sleep, repeating 4-5 times throughout the night.
The 4 Sleep Metrics
There are various physiological metrics like heart rate, breathing rate, sweating, or HRV that trackers will measure to assess four main sleep metrics.
Sleep Stages
Tracking sleep stages offers a detailed look at the balance between light sleep, deep sleep, and REM sleep throughout the night. Sleep trackers use data from motion, heart rate, or even brain activity to estimate time spent in each stage.
Understanding these stages provides insights into restoration, such as physical recovery during deep sleep and cognitive repair during REM sleep. Irregularities in sleep stage distribution, such as limited deep or REM sleep, can indicate stress, poor sleep hygiene, or underlying health issues, empowering users to take corrective actions.
Sleep Duration
Sleep duration measures the total time spent sleeping each night, a fundamental metric of sleep health. Sleep trackers can reveal whether individuals meet the recommended 7–9 hours of nightly sleep or fall short.
By consistently monitoring sleep duration, users can identify patterns of chronic sleep deprivation and adjust their schedules to prioritize rest.
Sleep Quality
Sleep quality goes beyond time in bed, offering a comprehensive look at how restorative the sleep experience is. Metrics like the number of awakenings, time spent in deep and REM sleep, and disruptions are analyzed to provide a sleep quality score.
The score helps users understand if their sleep is fragmented or unrefreshing despite adequate duration. Improving sleep quality—through better sleep environments, stress management, or optimized routines—can significantly enhance daytime energy and overall well-being.
Sleep Schedule
A consistent sleep schedule is essential for aligning the body’s internal clock, or circadian rhythm, with daily activities. Sleep trackers monitor when users go to bed and wake up, often revealing inconsistencies that might contribute to poor sleep quality or daytime fatigue.
By encouraging regularity and offering reminders or alarms, sleep trackers help users develop habits that support optimal sleep-wake cycles.
Is quality of sleep better than quantity?
Sleep quality is often more impactful than quantity. High-quality sleep ensures restorative deep and REM stages, supporting recovery and cognitive function, even if the total duration is slightly below the recommended range. However, chronic lack of adequate sleep duration still poses health risks. The general recommendation for healthy adults is around 7-9 hours of sleep each night.
What is a good sleep quality percentage?
A good sleep quality percentage, often calculated by sleep trackers, is generally above 85%. This score reflects factors like time spent in deep and REM sleep, minimal interruptions, and adherence to a consistent sleep schedule. The aim is increasing sleep score >90% by mini improvements in sleep habits like blocking blue light, avoiding stimulants, and creating an optimal sleep environment.
How much quality sleep is enough?
For most adults, achieving 1.5-2 hours of deep sleep and 1.5-2 hours of REM sleep each night is sufficient for recovery and cognitive function. This typically requires 7-9 hours of total sleep to accommodate these restorative phases.
The Benefits of Deep Sleep
Sleep is not just beneficial; it is essential for overall health and well-being. Sleep deprivation has been linked to weight gain, increased inflammation, and a higher risk of cardiovascular and metabolic diseases. (4) (5) (6) It also impairs cognitive functions such as memory, learning, and problem-solving. (7) (8)
Key benefits of quality sleep include:
- Enhanced Cognitive Function: Sleep consolidates memory, improves alertness, and supports problem-solving and executive function by balancing certain neurotransmitters. (9) (8)
- Improved Memory: Sleep reduces toxin buildup in the brain, protects neural function, and facilitates memory consolidation. (10) (11) (12)
- Cardiovascular Health: Sleep deprivation is associated with hypertension, cardiovascular diseases, and increased sympathetic tone. (13) (14) Quality sleep may therefore improve CVD metrics, and increase heart rate variability (HRV).
- Metabolic Health and Fat Loss: Sleep regulates hunger hormones like ghrelin and stress hormones like cortisol, enhancing energy metabolism, insulin sensitivity, and glucose utilization while reducing fat accumulation. (15) (16) (17) (18) (19)
In summary, sleep is vital for brain health, regeneration, cellular repair, and maintaining metabolic and cardiovascular health.
How Does a Sleep Tracker Help Improve Sleep?
A sleep tracker gives an objective insight into sleep metrics that determine overall sleep quality score. It makes it practical and easy to catch sleep deficits and determine the reason they occur.
Sleep tracking allows one to see things like:
- the detrimental impact of alcohol, sugars, or caffeine on sleep performance
- the detrimental impact of blue light and other stimulants before bed
- the impact of cold exposure or intense exercise on autonomic nervous system and HRV
- the actual consistency of one’s sleep schedule and its impact on total sleep duration
The point of monitoring and analyzing is to distinguish the bad sleep habits that deteriorate sleep, to try and change those for ones that increase sleep quality score.
The real practicality lies in seeing how such changes impact our sleep real-time. Beyond being profoundly motivating, it allows one to measure progress and determine trends over time
Are Sleep Trackers Accurate?
The gold standard for measuring sleep is electroencephalography (EEG), which tracks brain-wave activity. However, while highly accurate, EEG is impractical for everyday use. This has driven the growth of consumer-friendly sleep trackers that monitor sleep, fitness, and stress levels.
Sleep tracking devices are convenient, providing data through apps for easy analysis, but their accuracy varies. (20)
No sleep tracker matches the precision of EEG, and some may lack reliability. (21) However, many modern devices offer surprisingly accurate insights. (22) While a small margin of error is inevitable, the practical benefits of understanding sleep patterns often outweigh these limitations. (23)
Research shows that wearable trackers, such as rings, watches, or bands, tend to outperform contactless or noise-detecting devices in accuracy. For users seeking actionable sleep data, wearables remain the most reliable option in consumer technology. (21)
What Do Sleep Trackers Measure?
Sleep trackers use advanced yet simplified technologies to monitor key aspects of sleep. While not as comprehensive as polysomnography, which measures brain waves (EEG), muscle activity (EMG), and other physiological parameters, sleep trackers still provide valuable insights through various sensors.
- Accelerometers and Gyroscopes: Detect movement and positional changes during sleep.
- Heart Rate Monitoring: Tracks heart rate and heart rate variability (HRV) to assess stress and recovery levels.
- Electrodermal Activity (EDA) Sensors: Measure skin conductance, reflecting changes in physiological arousal.
- Temperature and Light Sensors: Monitor body temperature fluctuations and exposure to ambient light.
- Audio Monitoring: Detects ambient sounds, such as snoring or disturbances, to analyze sleep environment and quality.
By combining these data points with smart algorithms, sleep trackers provide an accessible and practical overview of sleep patterns and behaviors.
How does sleep tracking work?
Sleep tracking works by collecting data through wearable sensors or external devices that measure movement, heart rate, and other biometrics. Algorithms analyze these metrics to estimate sleep stages, total sleep time, and disturbances, providing insights into sleep patterns and quality.
What is the best way to record your sleep?
The gold standard for measuring sleep is EEG. The most practical way to record sleep daily is by using a reliable sleep tracking device like a ring or band with advanced sensors for heart rate, HRV, and motion tracking.
What is the best sleep tracker?
The Whoop Band 4.0 and Oura Ring are among the best commercial-grade sleep trackers due to their high accuracy, research-backed metrics, and advanced features like heart rate variability monitoring, sleep stage tracking, and personalized insights. Both provide detailed data for optimizing sleep and recovery.
The Most Accurate Sleep Trackers
The most precise consumer sleep trackers today are wearable devices such as rings and smart bands. Among them, these four trackers may be worth the investment, as they stand out for their accuracy and advanced features:
Whoop Band 4.0
Oura Ring
Known for its research-grade sensors, Oura monitors sleep stages, activity, stress, and temperature trends. Backed by extensive research, it is one of the most trusted devices in sleep tracking. *check the Pulse Blog for more research (27)
Ultrahuman Ring Air
A lightweight, comfortable ring featuring infrared PPG sensors to measure heart rate, HRV, and blood oxygen levels. It uses these metrics to generate a detailed sleep index score. (28)
Dreem 2
This headband-style sleep tracker is unique in its ability to measure sleep using electroencephalogram (EEG) sensors. It provides detailed insights into brain activity, making it closer to clinical-grade sleep monitoring. Dreem 2 also offers personalized sleep coaching based on comprehensive sleep analysis. It’s shown the highest reliability (76% on most nights) in a study assessing four different trackers. (29)
FitBit Versa 3
A reliable smartwatch that tracks sleep through motion and heart rate sensors, demonstrating comparable reliability to other sleep trackers. (29)
Honorable Mentions
Other notable options include Apple Watch Series 9, Fitbit Inspire 3, Withings Sleep, Biostrap EVO, Muse S, and Garmin Venu 3.
For those seeking research-backed, advanced sleep tracking, the Whoop Band 4.0 and Oura Ring remain the top choices.
