Understanding Rem Sleep: Measurement Techniques And Insights

Sleep is a complex and fascinating aspect of human physiology, and while we sleep, we cycle through various stages of sleep, including REM sleep. REM stands for rapid eye movement, and this stage is characterised by quick eye movement, irregular breathing, an elevated heart rate, and increased brain activity. While we don't have a full understanding of the purpose of sleep, we do know that REM sleep is important for memory, emotional processing, brain development, and dreaming.

REM sleep is usually measured with a polysomnogram, which is a comprehensive assessment that uses an electroencephalogram (EEG) to diagnose sleep disorders. This records brain waves, blood oxygen levels, and heart rates, as well as measuring breathing and eye and leg movements. Other methods of measuring REM sleep include using wearables such as Fitbit, Garmin, and Apple Watch, as well as sleep diaries and wrist actigraphy.

REM sleep is measured using a polysomnogram, which records brain waves, blood oxygen level, heart rate, breathing, eye and leg movements

Sleep is measured primarily using polysomnography (PSG), which is considered the gold standard for diagnosing sleep disorders. PSG reveals that sleep architecture has several distinct stages that vacillate between the non-rapid eye movement (NREM) and rapid eye movement (REM) stages.

The gold standard of physiological monitoring is the polysomnogram (PSG). This method is used to identify the three stages of NREM sleep (N1-N3) and the REM sleep stage by measuring specific EEG waveform rhythms and events.

REM sleep can also be measured with electrooculography (EOG), an assessment used to determine sleep patterns and how long one stays in the REM sleep stage. Dreaming occurs during the REM stage, and the eyes make specific movements, which help sleep specialists determine REM sleep quality and the length of time spent in this stage.

"Wearables" or devices worn on the body can also be used to detect sleep patterns, hygiene, and health. Common "wearables" that can help determine REM sleep quality include Fitbit, Garmin, and Apple Watch.

Wearables such as Fitbit, Garmin, and Apple Watch can be used to measure REM sleep

Fitbit devices such as the Fitbit Alta HR, Fitbit Charge 3, Fitbit Versa, Fitbit Ionic, and Charge 4 can tap into your nighttime heart rate and movement patterns to estimate how much time you spend in light, deep, and REM sleep. Fitbit groups similar sleep stages together, so in the app, your sleep will fall into three stages: light, deep, and REM. Each of these stages, or sleep types, serves a different purpose, so understanding how much time you spend in each stage can help you identify and address sleep-related issues.

Garmin also offers advanced sleep monitoring features on its wearables, although the specifics of these features are not readily available.

With the Sleep app on Apple Watch, you can create sleep schedules to help you meet your sleep goals. When you wear your watch to bed, Apple Watch can estimate the time spent in each sleep stage: REM, Core, and Deep. In the morning, you can open the Sleep app to learn how much sleep you got and see your sleep trends over the past 14 days. Additionally, your Apple Watch can help track your breathing rate as you sleep, providing greater insight into your overall health.

Electrooculography (EOG) is used to determine sleep patterns and the length of the REM sleep stage

Electrooculography (EOG) is a method that measures the corneo-retinal standing potential to map the eye's position. It is frequently the method of choice for recording eye movements in sleep research. EOG is used to distinguish between the rapid eye movement (REM) and non-rapid eye movement (NREM) stages of sleep. During wakefulness, rapid eye movements may be very frequent or rare, depending on the extent to which vision is being used. Eye movement is absent during NREM sleep.

EOG is composed of two rhythms: slow eye movements (SEMs) and rapid eye movements (REMs). During the REM stage, there are bursts of rapid eye movements in the recording, sometimes between REMs there are periods of no eye movements. Slow rolling eye movements are one of the first indicators of sleep onset and are present during stage 1.

EOG is one of the three types of electrophysiological signals that are mandatory to properly identify wakefulness, non-REM (NREM) sleep, REM sleep, and arousals. The other two signals are electroencephalography (EEG) and electromyography (EMG). The recording of these signals requires at least three scalp EEG electrodes, two EOG electrodes placed on either side of the eyes, and two chin EMG electrodes.

EOG is also recorded with a referential montage, with both EOG electrodes referenced to the same mastoid electrode. The placement of EOG electrodes can detect conjugate horizontal and vertical eye movements. For example, when the eyes look to the right, the cornea of the right eye approaches the positive electrode, and the amplifier registers a downward deflection.

EOG has been used in various studies to detect driver hypovigilance, sleep staging, and sleep disorders such as insomnia, narcolepsy, and REM behaviour disorder.

REM sleep deprivation can negatively affect health and well-being, causing sleepiness and drowsiness

Sleep is measured primarily by polysomnography (PSG), which is considered the gold standard for diagnosing sleep disorders. PSG reveals that sleep architecture has several distinct stages that vacillate between the non-rapid eye movement (NREM) stages and rapid eye movement (REM) stages.

The effects of REM sleep deprivation can be both immediate and long-term. In the short term, people may experience fatigue, irritability, changes in mood and memory, and issues with cognition and problem-solving. Over time, chronic sleep deprivation can contribute to various health conditions, including obesity, metabolic disorders, cardiovascular issues, and an increased risk of Type 2 diabetes. It may also increase the risk of cancer, stroke, and neurodegenerative diseases like Alzheimer's.

Additionally, REM sleep deprivation can impact mental health, making it harder to manage and process emotions. People with sleep deprivation are more likely to experience symptoms of depression and anxiety. It can also affect pain tolerance and sensitivity, making it difficult to tolerate pain and increasing sensitivity.

To increase REM sleep and improve overall sleep quality, it is recommended to maintain a regular sleep schedule, avoid stimulants and alcohol, exercise regularly, limit the use of electronic devices before bed, and avoid heavy meals close to bedtime.

REM sleep plays a role in memory consolidation, emotional processing, brain development, and dreaming

REM sleep is the fourth and final stage of sleep, characterised by relaxed muscles, quick eye movement, irregular breathing, an elevated heart rate, and heightened brain activity. It is also known as active sleep, desynchronized sleep, paradoxical sleep, rhombencephalic sleep, and dream sleep.

Memory Consolidation

REM sleep is important for memory consolidation. During this stage, the brain processes new learnings and motor skills from the day, deciding what to commit to memory, what to maintain, and what to delete.

Emotional Processing

REM sleep is also when the brain processes emotions. Dreams, which are more vivid during REM sleep, may be involved in this process. The amygdala, the part of the brain that processes emotions, is activated during this stage.

Brain Development

REM sleep is thought to promote brain development, as newborns spend most of their sleep time in this stage. Additionally, animals born with less developed brains, such as humans and puppies, spend more time in REM sleep during infancy than those born with more developed brains, like horses and birds.

Dreaming

REM sleep is associated with dreaming. While dreams can occur during non-REM sleep, they are usually more vivid during REM sleep.

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