Rem Sleep Absence: Polysomnogram Anomaly Explained

Polysomnography is a sleep study that records body functions as you sleep or try to sleep, and it is used to diagnose sleep disorders. During a polysomnogram, electrodes are placed on your chin, scalp, and the outer edge of your eyelids, and monitors are attached to your chest to record your heart rate and breathing. The test measures the amount of time it takes you to fall asleep and enter REM sleep, and it can be performed at a sleep center or at home. While it is unusual not to have REM sleep during a polysomnogram, it is not impossible, and there are several reasons why this may be the case.

REM sleep is the fourth stage of sleep, characterised by relaxed muscles, quick eye movement, irregular breathing, an elevated heart rate, and increased brain activity

Rapid eye movement (REM) sleep is the fourth and final stage of sleep. During this stage, the body experiences a range of changes, including:

• Relaxed muscles: The body experiences a temporary loss of muscle tone, except for the eyes, which move rapidly.
• Quick eye movement: The eyes move rapidly behind closed eyelids.
• Irregular breathing: Breathing becomes faster and more irregular.
• Elevated heart rate: The heart rate rises to near-waking levels.
• Increased brain activity: Brain activity is more similar to wakefulness than in other sleep stages.

REM sleep typically occurs about 60 to 90 minutes after falling asleep and is associated with dreaming and memory consolidation. It plays a crucial role in memory, emotional processing, and brain development. Most adults require approximately two hours of REM sleep each night.

REM sleep is just one part of the complex process of sleep, which is essential for the body and brain to rest and recover. Sleep is typically divided into non-REM (NREM) sleep and REM sleep, with distinct patterns of brain activity and physiological changes. While NREM sleep consists of three stages of increasingly deeper sleep, REM sleep is characterised by heightened brain activity and unique physiological changes.

Most adults need about two hours of REM sleep per night

Sleep is a complex and mysterious process that is essential for the body and brain to function properly. Most adults need seven to nine hours of sleep per night, including about two hours of REM sleep.

REM sleep is the fourth of four stages of sleep. It is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. It usually occurs about 60 to 90 minutes after falling asleep, and each cycle through the four stages of sleep takes 90 to 120 minutes to complete.

During REM sleep, the body experiences a temporary loss of muscle tone, while the eyes move rapidly, the heart rate increases, and breathing becomes irregular. The brain is highly active during this stage, with brain waves resembling those when a person is awake.

REM sleep is important for several reasons. Firstly, it plays a role in memory consolidation, helping the brain process and store new information. Secondly, it aids in emotional processing by allowing the brain to regulate emotions. Thirdly, it is involved in brain development, especially in infants and children whose brains are still developing. Finally, it is associated with dreaming, with most dreams occurring during this stage.

While most adults need about two hours of REM sleep per night, this can vary from person to person. Some people may need more or less REM sleep, and this can even be influenced by genetic factors. Additionally, personal circumstances and health status can also impact the amount of REM sleep required.

Overall, REM sleep is a crucial component of a good night's rest, contributing to the body's recovery and maintenance processes.

REM sleep is important for memory consolidation, emotional processing, brain development, and dreaming

It is unusual not to have REM sleep during a polysomnogram, as it is the fourth out of four total stages of sleep. During a full night's sleep, you cycle through four stages of sleep multiple times: three stages of non-REM sleep, followed by one stage of REM sleep.

Memory Consolidation

During REM sleep, your brain processes new learnings and motor skills from the day, deciding which ones to commit to memory, maintain, and delete. This is similar to a librarian sorting and shelving books at the end of the day, making it easier to access and retrieve information.

Emotional Processing

REM sleep is associated with dreaming, and dreams may be involved in emotional processing. Your amygdala, the part of your brain that processes emotions, activates during REM sleep. Studies suggest that being deprived of REM sleep interferes with memory formation, which is linked to emotional processing.

Brain Development

REM sleep is hypothesized to promote brain development, especially in newborns who spend most of their sleep time in this stage. This is supported by the fact that 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

A majority of your dreams occur during REM sleep, and they are usually more vivid than non-REM dreams. The rapid eye movements during this stage earned it the name "REM sleep."

Polysomnography is a sleep study used to diagnose sleep disorders

Polysomnography can be used to diagnose various sleep-related conditions, such as sleep apnea, periodic limb movement disorder, certain types of seizures, and epilepsy. It can also help identify issues with brain function, nervous system function, breathing, and heart function.

The test involves several types of sensors and monitoring methods to track different body systems and processes. Electroencephalography (EEG) sensors, for example, are used to detect and record electrical activity in the brain, while electrocardiography (EKG or ECG) monitors heart activity. Other sensors track muscle movement, eye activity, air movement during breathing, and the level of oxygen in the blood.

Polysomnography can be performed at a sleep center or in a person's home, depending on the specific situation and needs of the individual. It is a valuable tool for healthcare providers to diagnose and treat sleep disorders.

REM sleep behaviour disorder (RBD) is a parasomnia in which people physically act out their dreams

RBD occurs during the REM sleep phase, which starts about 60 to 90 minutes after falling asleep. During a full night's sleep, people typically cycle through four stages of sleep multiple times: three stages of non-REM sleep followed by one stage of REM sleep. Each cycle through all the sleep stages takes 90 to 120 minutes to complete, with each new cycle spending increasing amounts of time in REM sleep.

The symptoms of RBD can vary in severity, and people with this disorder may not be aware of their actions during sleep. In some cases, people only find out they have RBD when their bed partner or roommate tells them about their behaviour or when they wake up with an injury. About 8 in 10 people with RBD experience sleep-related injuries, and it can also cause frequent sleep disruptions, affecting their overall quality of sleep.

RBD is a relatively rare disorder, affecting about 1% of the general US population and 2% of people aged 50 or older. However, the rates may be higher as RBD can be difficult to diagnose, and almost half of those with the condition are unaware they have it. It is important to seek treatment for RBD to prevent accidental injuries to oneself or one's bed partner.

The main treatment goal for RBD is to create a safe sleeping environment. This can include removing sharp and heavy objects from the bedroom, placing pillows or cushions around the bed, and sleeping on the ground floor if possible. If symptoms are severe, it may be safest for the bed partner to sleep in a separate room. Additionally, it is recommended to avoid alcohol, as it can trigger RBD episodes and make the condition worse.

In cases where safety measures are insufficient to prevent injury, healthcare providers may prescribe medication to manage symptoms. While there are no FDA-approved medications specifically for RBD, studies have shown that melatonin, clonazepam, and pramipexole can reduce symptoms. Melatonin is typically the first-line medication due to its rare side effects, and other medications are usually only prescribed if melatonin is ineffective.

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