Measuring Rem Sleep: Home-Based Techniques And Insights

Sleep is an essential part of a healthy lifestyle, and the quality of sleep can be measured through various methods. Sleep disorders are a global epidemic, affecting millions of people's health and quality of life. Monitoring sleep can help diagnose and address these issues, and new technologies have made it possible to do so from the comfort of home. This article will explore the different ways to measure REM sleep at home, including wearables, sleep diaries, and smart home devices.

Electroencephalography (EEG)

EEG is used to measure brain rhythms, and while the function of these rhythms is unknown, they have been correlated with different behavioural states such as wakefulness, sleep, and attentiveness. EEG can be used to measure brain activity during different behavioural states and is used in both research and the diagnosis of various neurological conditions such as sleep disorders and epilepsy.

EEG detects the general activity of the cortex by measuring small (~10 uV) fluctuations in voltage. This technique does not measure the electrical activity of a single neuron but instead measures the electrical activity of thousands of cells to generate a signal that is large enough to detect. An increase in amplitude on an EEG indicates a higher degree of synchronous activity of cortical neurons, while the frequency of an EEG indicates how often neural synchrony occurs.

EEG recordings are typically taken from a 10-20 electrode system, with distinct landmarks on the head and electrodes placed at 10% or 20% intervals of the distance between these landmarks. The number of electrodes used depends on the purpose of the study.

EEG is the only way to see how much REM sleep one is getting, as it measures brainwaves. A headband placed on the forehead can pick up the signals being sent throughout the brain, showing what stage of sleep one is in and for how long. This is called sleep architecture.

EEG has been found to have strong and substantial epoch-by-epoch agreement with polysomnography (PSG), which is the gold standard for sleep monitoring. However, the agreement decreases when there are frequent sleep-wake or other sleep stage transitions.

Wearables

The Oura Ring is one of the most popular options. It's a stylish, lightweight ring that measures your respiratory rate, heart rate, heart-rate variability (HRV), blood-oxygen levels, and body temperature. It then combines this data with your activity and movement, logged via an accelerometer, to give you three daily scores: Sleep, Activity, and Readiness. The Oura Ring has been proven to be highly accurate when compared with a heart-rate sensor and polysomnography test, and its data is easy to interpret via its app. However, it struggles with categorising certain types of exercise, and it requires a monthly subscription to access most features.

The Whoop 4.0 is another highly-rated wristband sleep tracker. It uses photoplethysmography and LEDs to shine a light on your skin and translate the differences in light absorption and reflection into changes in blood flow, which is how it calculates heart rate and heart-rate variability. It also has an accelerometer to track motion. The Whoop app provides in-depth activity and recovery tracking, and its battery is removable, so you can charge it on the go. However, the app has an intimidating interface and requires a lot of user input. It also has an expensive subscription plan.

The Fitbit Inspire 3 is a good option for those who want to measure physical activity and sleep data without a bulky device on their wrist. It has a sleek design, a small digital screen, and impressive battery life, all for a very affordable price. However, its recorded sleep time has been found to be inaccurate at times, and its advanced features require a subscription.

The Samsung Galaxy Ring is a good option for Android users who want to consolidate their devices and track their sleep, workouts, and other health metrics. It measures heart rate, snoring, energy, blood oxygen, stress, skin temperature, menstrual cycle, activity, and sleep performance. It's also slightly lighter and thinner than the Oura Ring, and it has a beautifully designed charging case. However, it requires a newer Galaxy phone to access all features, and it doesn't track HRV.

The Dreem headband is a battery-powered, AI-enabled headband made from lightweight, waterproof foam. It has five electroencephalogram (EEG) sensors that measure brain activity, a pulse oximeter to monitor heart rate, and an accelerometer to record movement and breathing during the night. This data is analysed by a deep learning algorithm and, when combined with the Dreem smartphone app, provides daily reports and insights on the user's sleeping habits. The headband can also be used to improve sleep quality, using soothing audio features based on the readings it picks up in real time. However, it is expensive, costing £359 ($465).

The Apple Watch Series 9 can also be used to track your sleep if you already have one. It breaks your slumber down into four stages and can also measure blood oxygen and temperature. It has a Wind Down feature to help with your bedtime routine and gentle alarms in the morning. However, it doesn't provide an overall sleep score, and the charts are hard to read.

Lastly, the Ultrahuman Ring Air is a lightweight ring with a medical-grade temperature sensor, a PPG (photoplethysmography) sensor, and a motion-sensing IMU (inertial measurement unit). It has been found to be highly accurate in measuring sleep stages and duration, and the accompanying app provides valuable advice. However, it has trouble with workout recording.

Polysomnography (PSG)

PSG is considered the gold standard for diagnosing sleep-related breathing disorders, such as obstructive sleep apnea (OSA), central sleep apnea, and sleep-related hypoventilation/hypoxia. It can also be used to evaluate other sleep disorders, including nocturnal seizures, narcolepsy, periodic limb movement disorder, and REM sleep behaviour disorder.

PSG involves a systematic process of collecting physiological parameters during sleep. A polysomnogram utilises an electroencephalogram (EEG), electro-oculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), and pulse oximetry, as well as airflow and respiratory effort, to evaluate the underlying causes of sleep disturbances.

During a PSG, a minimum of 12 channels are recorded, requiring a minimum of 22 wire attachments to the patient. These channels can be adapted to meet the doctor's requests and may vary between labs. The wires for each channel of recorded data converge into a central box, which is connected to a computer system for recording, storing, and displaying the data.

• A minimum of three channels for EEG to measure brain activity. Electrodes are typically placed near the frontal, central, and occipital portions of the brain.
• One or two channels to measure airflow using pressure transducers or a thermocouple.
• One or two channels for chin muscle tone (EMG).
• One or more channels for leg movements (EMG).
• Two channels for eye movements (EOG).
• One or two channels for heart rate and rhythm (ECG).
• One channel for oxygen saturation (pulse oximetry).
• One channel each for belts that measure chest wall and upper abdominal wall movement.

PSG can be performed as an overnight sleep study in a lab or as an unattended home sleep test. Type I PSG is the overnight study monitored by a credentialed technologist, while Type II-IV PSG refers to the home sleep tests. It is important to note that PSG should only be performed by technicians and technologists specifically accredited in sleep medicine.

Wrist actigraphy

The data collected by the actigraph is based on the assumption that sleep is associated with reduced movement, and so the absence of movement is used as a surrogate for sleep. The device contains an accelerometer that records movement, a data storage unit, and a programmable timing mechanism. It does not require any preparation or setup and can be worn for several days or even weeks, providing an objective measure of an individual's sleep patterns over a prolonged period.

The data collected by the actigraph can be used to calculate various sleep parameters, including the time an individual falls asleep and wakes up, how long they take to fall asleep, their total sleep time, and how much time they spend awake during the night. This information can help medical professionals identify any irregularities in an individual's sleep schedule and can be used to diagnose and monitor treatment for certain sleep disorders, such as insomnia, circadian rhythm sleep-wake disorders, and insufficient sleep syndrome.

While wrist actigraphy is a useful tool for measuring sleep, it has some limitations. It does not measure sleep stages and relies solely on movement to determine sleep patterns. As a result, it may overestimate sleep duration, especially in individuals who spend a lot of time awake but immobile in bed. Additionally, it may not be as accurate for people with limited mobility or certain sleep disorders, such as sleep apnea, where frequent movements and arousals may interfere with the device's accuracy.

Despite these limitations, wrist actigraphy is a widely used method for evaluating sleep and can provide valuable insights into an individual's sleep habits and patterns. It is often used in conjunction with other methods, such as sleep logs or overnight sleep tests, to complement and validate the data.

Sleep diary

Keeping a sleep diary is an easy and affordable way to track your REM sleep quality. However, it is important to note that sleep diaries rely on self-reported data, which can be subjective and unreliable. They may not accurately reflect your sleep patterns and stages.

• Record bedtime and wake-up time: Note the time you go to bed and the time you wake up. This will help you calculate your total sleep duration.
• Track sleep quality: Take note of any disturbances or interruptions during your sleep. Did you toss and turn, or wake up multiple times during the night?
• Monitor sleep latency: How long does it take you to fall asleep after getting into bed? This can give you insights into your sleep efficiency.
• Log lifestyle factors: Record information about activities and substances that can impact your sleep. This includes caffeine and alcohol consumption, exercise, stress levels, and any medications you are taking.
• Reflect on dreams: Dreams are a characteristic of REM sleep. Write down any vivid dreams or nightmares you recall upon waking.
• Consistency is key: Aim to fill out your sleep diary every day, even on days when you feel you had a good night's sleep. This will help you identify patterns over time.
• Use a sleep diary in conjunction with other methods: Consider combining your sleep diary with wearable sleep trackers or sleep-tracking apps to gain a more comprehensive understanding of your sleep habits.

Frequently asked questions