REM sleep behavior disorder

Rapid eye movement sleep behavior disorder (RBD) is a sleep disorder where people act out their dreams due to a loss of normal muscle paralysis (atonia) during rapid eye movement (REM) sleep ¹, ², ³. This can lead to dangerous movements, such as punching or falling out of bed. Normally during REM (rapid eye movement) sleep, the body experiences temporary paralysis of most of the body’s muscles known as atonia while the brain is active and dreaming. Blood pressure rises, breathing becomes irregular, and the eyes dart in all directions rapidly hence, the term “rapid eye movement” (REM). The temporary paralysis of REM sleep allows you to dream quietly and safely throughout the night, lying still while your brain is active. This paralysis involves most skeletal muscles and excludes muscles that help us breathe, digest, and some muscles of the eyes. REM sleep accounts for about 25 percent of a total night’s sleep, with most of it taking place during the second half of the night.

For individuals with rapid eye movement sleep behavior disorder (RBD), paralysis does not occur during the REM stage. Instead, their body and voice perform their dreams while they remain asleep. REM sleep behavior disorder (RBD) can manifest as small muscle twitches and quiet sleep talking to loud shouting, punching, kicking, grabbing their bed partner, and jumping out of bed. Interestingly, the dreams associated with REM sleep behavior disorder (RBD) are often intense and frightening. Individuals may dream about being chased or attacked, and they can unknowingly enact the dream in real life.

Due to the potentially violent nature of their movements, individuals with REM sleep behavior disorder (RBD) can put themselves and anyone they share their bed with at risk of physical injury. Depending on the nature of the dream and their bedroom environment, these injuries can be life-threatening. Up to 90 percent of spouses of those with REM sleep disorder report having sleep issues and over 60 percent have experienced a physical injury ⁴. Even when the potential for physical injury has been reduced, the disruption of sleep to the individual or their sleep partner can still be severe enough to cause relationship problems. However, nearly two-thirds of couples continue sleeping together despite the risk of disturbed sleep.

Scientists do not know what causes REM sleep behavior disorder (RBD). Animal studies suggest that it has to do with certain neural pathways in the brain. In an individual without REM sleep behavior disorder (RBD), certain neural pathways inhibit muscle activity during REM sleep, and disruption in these neural pathways lead to REM sleep without atonia.

Less than one percent of people are estimated to have REM sleep behavior disorder (RBD) ⁵. Rapid eye movement sleep behavior disorder (RBD) usually begins after age 50, and the disease is associated with other neurodegenerative disorders, including Parkinson’s disease, Lewy body dementia, and multiple system atrophy ³. One study found that 38 percent of men aged 50 or older with REM sleep behavior disorder (RBD) eventually developed Parkinson’s disease, Lewy body dementia, or multiple symptom atrophy, usually within 13 years ⁶.. That number increased to nearly 81 percent in a followup study conducted 16 years later ⁷. These findings have been confirmed in subsequent research; 30 percent of individuals with REM sleep disorder developed a Parkinsonian disorder or dementia within 3 years and 66 percent did so within 7.5 years ⁸.

REM sleep disorder can also be brought on by antidepressants, including tricyclic antidepressants and serotonin-specific reuptake inhibitors ⁹.

Risk factors for REM sleep behavior disorder (RBD) include ³:

• Being male
• Being over 50 years old
• Having another neurological disorder, like Parkinson’s disease, Lewy body dementia, or multiple system atrophy
• Having narcolepsy
• Using some medications or antidepressants ¹⁰
• Use or withdrawal from drugs or alcohol ¹¹

Typically, REM sleep behavior disorder is a disease of elderly persons with the average age of onset of about 61 years of age although the disease may occur at any age including in childhood, with 87 percent being male ¹², ¹³, ¹². In a report by Olson et al involving 93 patients with REM sleep behavior disorder, only 12 patients (13%) were female ¹⁴.

More research is needed to understand environmental contributors to REM sleep behavior disorder. Sleep deprivation, smoking, head injury, and exposure to pesticides may be environmental risk factors.

According to the American Academy of Sleep Medicine’s International Classification of Sleep Disorders 3rd edition (ICSD-3), a person must meet four criteria to receive a diagnosis of REM sleep behavior disorder (RBD) ¹⁵:

1. You have repeatedly experienced episodes of acting out your dreams with vocalizations or arm and leg movements that correspond to what’s taking place in your dream.
2. Episodes occur during REM sleep, as confirmed by an in-laboratory polysomnogram (in-lab sleep study) or your clinical history.
3. Episodes include sleep without atonia, as confirmed by polysomnography.
4. The episodes are not attributed to something else, like another sleep or mental health disorder, a side effect of medication, or substance abuse.

If you think you may have REM sleep behavior disorder (RBD), it’s best to consult your doctor. Your doctor may then refer you to a sleep physician. Here’s what you can expect to happen when you meet with them.

• First, your doctor will conduct a physical and neurological exam. The point of this is to rule out any other potential causes, like alcohol, medications, or narcolepsy, a sleep disorder that often coexists with REM sleep behavior disorder (RBD) ¹⁶
• Due to the common co-occurrence of Parkinsonian syndromes and REM sleep behavior disorder (RBD), your doctor will also look for symptoms of Parkinson’s disease, such as hand tremors or muscle stiffness.
• If you sleep with a partner, your doctor may ask them if they’ve seen you act out your dreams while you sleep. They’ll ask them to describe the dream enactment behaviors they observed.

Your doctor may refer you to a sleep lab for a polysomnogram, an overnight sleep study. During the study, sensors monitor your breathing, eye movements, arm and leg movements, brain and heart activity, and blood oxygen levels. It’s common to videotape the exam to record any dream enactment behavior.

After the exam, a sleep physician will review your medical history, symptoms, and the results of your polysomnogram to determine whether a diagnosis of REM sleep behavior disorder (RBD) is appropriate.

The treatment for REM sleep behavior disorder (RBD) is tailored to an individual and can involve a combination of lifestyle changes, medication, and injury prevention techniques.

Avoiding Triggers

Because the use of certain alcohol or prescription drugs can contribute to REM sleep behavior disorder, making lifestyle changes to reduce or eliminate their use may be part of a person’s treatment. These changes can be part of a larger set of steps to improve sleep hygiene, such as setting a consistent sleep schedule, that normalize sleep and promote sleep quality.

Medications

Melatonin is the preferred, first-line medication for REM sleep behavior disorder. It usually has fewer side effects than other medication options but has similar efficacy ¹⁷. Melatonin is also a safer option for elderly individuals, individuals with dementia, fall risk, or those with sleep apnea. The dosage of melatonin one should take for REM sleep behavior is different than when taking it to fall asleep, and you should consult a sleep physician.

The prescription drug clonazepam has proven effective in reducing symptoms for 50-80% of individuals with REM sleep disorder ¹⁸. However, it can cause some side effects, including sleepiness, forgetfulness, and impaired balance in the morning. It can also contribute to or worsen sleep apnea ¹⁹.

Always consult a doctor before taking any prescription or over-the-counter medication. They can best advise you on a treatment plan based on your medical history and symptoms.

Injury Prevention Techniques

Establishing a safe sleep environment is one of the most important things someone with REM behavior sleep disorder can do. Sleep-related injuries — including bruising, cuts, fractures, blunt trauma, and head trauma have been reported among 30 to 81 percent of individuals with REM sleep behavior disorder. In addition, the bed partner is also at risk for injury when they are sleeping next to someone who unknowingly acts out violent dreams

Recommendations for injury prevention may include:

• Removing sharp objects and weapons from the bedroom
• Placing padding on the floor around the bed
• Installing padded bed rails on the side of the bed
• Putting the mattress on the floor
• Moving furniture and clutter away from the bed
• Padding the corners of furniture in the bedroom
• Protecting bedroom windows

If the individual shares their bed with a sleep partner, it may also be recommended that they sleep in separate beds or separate rooms until symptoms are well treated.

Sleep Stages

Sleep occurs in 2 main phases, Non-Rapid Eye Movement (NREM) sleep, which has three stages (N1, N2, and N3), and Rapid Eye Movement (REM) sleep ²⁰. Each sleep phase and stage of sleep includes variations in muscle tone, brain wave patterns, and eye movements. Your body cycles through all stages approximately 4 to 6 times each night, averaging 90 minutes for each cycle ²¹. Each sleep stage serves different functions, from the light transition into sleep (N1), to the restorative deep sleep (N3) and the active dreaming of REM sleep.

Sleep Stages ²², ²³:

• Stage 1 (N1 or light sleep) is the lightest stage of sleep and occurs as a person first falls asleep. This brief stage is when your drowsiness gives way to falling asleep. Your heartbeat and breathing start to slow down, but it’s still pretty easy to wake you up during this stage. Average length 1 to 7 minutes.
• Stage 2 (N2 or intermediate sleep) is where the body starts to relax more deeply. Your body temperature drops, your muscles relax, and your breathing and heart rate slow even more. Average length 10 to 25 minutes.
• Stage 3 (N3 or deep sleep) is the deepest and more restorative sleep, allowing your body to recover and grow. In stage 3 sleep, your breathing and pulse are slow and steady. Average length 20 to 40 minutes.
• Stage 4 (REM Sleep) is where most dreaming occurs, brain activity increases almost as if you were awake, and your muscles become temporarily paralyzed. Your heart rate and respiration speed up and become more erratic, and your eyes move quickly behind your eyelids. Dreams are most vivid during the REM stage. Average length 10 to 60 minutes.

Although the sleep stages are described numerically, you don’t always progress through them in this exact order. For example, in many sleep cycles, you transition from stage 3 sleep back to stage 2 sleep before beginning a period of REM sleep.

Sleep occurs in 5 stages: Wake, Non-Rapid Eye Movement (NREM) stage N1, then progress through N2 and N3, and after N3 you enter REM sleep ²⁰. You then return to NREM stages, often starting again at N2. Throughout the night, the REM periods lengthen, and deep N3 sleep decreases, with most N3 sleep occurring in the first half of the night, with each stage leading to progressively deeper sleep. Approximately 75% of sleep is spent in the NREM (Non-Rapid Eye Movement) stages, with the majority spent in the N2 stage ²⁴. A typical night’s sleep consists of 4 to 5 sleep cycles, with the progression of sleep stages in the following order: N1, N2, N3, N2, REM ²⁵. A complete sleep cycle takes roughly 90 to 120 minutes. The first REM period is short, and as the night progresses, longer periods of REM and decreased time in deep sleep (NREM) occur ²⁰. With each new cycle, you spend increasing amounts of time in REM sleep, so most of your REM sleep takes place in the second half of the night.

Sleep isn’t uniform. Sleep cycles can vary from person to person and from night to night based on a wide range of factors such as your age, recent sleep patterns, and alcohol consumption. Over the course of the night, you go through several rounds of the sleep cycle, which is composed of four stages. In a typical night, a person goes through four to six sleep cycles ²⁰. Not all sleep cycles are the same length, but on average they last about 90 minutes each.

The first sleep cycle is often the shortest, ranging from 70 to 100 minutes, while later cycles tend to fall between 90 and 120 minutes. In addition, the composition of each cycle — how much time is spent in each phase of sleep — changes as the night goes along.

Figure 1. Sleep Stages

Footnotes: A sleep episode begins with a short period of NREM stage N1 progressing through stage N2, followed by stage N3 and finally to REM. However, individuals do not remain in REM sleep the remainder of the night but, rather, cycle between stages of NREM and REM throughout the night. NREM sleep constitutes about 75 to 80 percent of total time spent in sleep, and REM sleep constitutes the remaining 20 to 25 percent. The average length of the first NREM-REM sleep cycle is 70 to 100 minutes. The second, and later, cycles are longer lasting—approximately 90 to 120 minutes ²⁶. In normal adults, REM sleep increases as the night progresses and is longest in the last one-third of the sleep episode. As the sleep episode progresses, stage 2 begins to account for the majority of NREM sleep, and stages 3 and 4 may sometimes altogether disappear.

[Source ²² ]

Figure 2. Typical Sleep Pattern in Young Adults 

Footnotes: Average times and sequences of sleep cycles during the night. Over the course of a period of sleep, NREM and REM sleep alternate cyclically. The function of alternations between these two types of sleep is not yet understood, but irregular cycling and/or absent sleep stages are associated with sleep disorders ²⁷. For example, instead of entering sleep through NREM, as is typical, individuals with narcolepsy enter sleep directly into REM sleep ²⁸. Rapid eye movement (REM) sleep occurs cyclically throughout the night every 90 to 120 minute. Brief periods of wakefulness (stage W) occur periodically.  Sleep time is spent as follows:

• Stage N1: 2–5%
• Stage N2: 45–55%
• Stage N3: 13–23%
• REM: 20–25%

[Source ²⁹ ]

Figure 3. EEG activity of the four stages of sleep

Footnotes: EEG activity during wakefulness with eyes open and closed and during the different stages of sleep. Brainwave activity changes drastically over the course of the different stages of sleep. REM sleep brain activity most closely resembles brain activity while awake.

• Alpha activity is a smooth electrical activity of 8-12 Hz recorded from the brain; generally associated with a state of relaxation during wakefulness.
• Beta activity is a irregular electrical activity of 13-30 Hz recorded from the brain; generally associated with a state of alertness during wakefulness.
• Theta activity is EEG activity of 3.5-7.5 Hz that occurs intermittently during lighter stages of NREM sleep.
• Delta activity is a regular, synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep.
• Sleep spindle is a short burst of 12 to 14 cycle per-second waves observed during NREM sleep, decrease brain’s sensitivity to sensory input and keeps person asleep.
• K complex are single delta waves, sudden sharp wave forms, 1 per minute but can be triggered by noise.

[Source ³⁰ ]

Your sleep-wake cycle is regulated by the circadian rhythm (your body’s natural internal 24-hour clock that manages your sleep-wake cycle and other vital functions, like hormone release and body temperature, by synchronizing with the day-night cycle), which is driven by the suprachiasmatic nucleus (SCN) of the hypothalamus that acts as a “master clock” or “circadian pacemaker”, receiving light cues from your eyes to control the circadian rhythm ³¹, ³², ³³. The circadian rhythm also controls the nocturnal release of adrenocorticotropic hormone (ACTH), prolactin, melatonin, and norepinephrine (NE) ³⁴. External factors like light exposure, meal timing, and activity can influence the circadian rhythm, and disruptions to the circadian rhythm, such as from shift work or jet lag, can negatively affect your health.

The suprachiasmatic nucleus (SCN) of the hypothalamus receives input from nerve cells in the retina that detect light to regulate the circadian rhythm and sleep via multiple pathways that cause the nocturnal release of adrenocorticotropic hormone (ACTH), prolactin, melatonin, and norepinephrine ³⁵. One of the most commonly recognized pathways by which this occurs is via the stimulation of norepinephrine release by the suprachiasmatic nucleus (SCN), which in turn stimulates the pineal gland to release melatonin ³⁶, ³³. Wakefulness is maintained by subcortical structures and pathways activating the cortical system ³⁶. This system is termed the “ascending arousal system” and utilizes several major neurochemicals, including:

• Norepinephrine (locus ceruleus)
• Serotonin (midline raphe nuclei)
• Histamine (tuberomammillary nucleus)
• Dopamine (ventral periaqueductal gray matter)
• Acetylcholine (pedunculopontine tegmentum and laterodorsal tegmentum of the pons)
• Orexin (perifornical area)

Transitions between sleep and wake states are influenced by multiple brain structures, including ²⁰:

• Hypothalamus: controls onset of sleep
• Hippocampus: memory region active during dreaming
• Amygdala: emotion center active during dreaming
• Thalamus: prevents sensory signals from reaching the cortex
• Reticular formation: regulates the transition between sleep and wakefulness
• Pons: helps initiate REM sleep. The extraocular movements (eye movements) that occur during REM sleep are due to the activity of PPRF (paramedian pontine reticular formation/conjugate gaze center).

Although it is apparent that humans need sleep, the current understanding of why sleep is an essential part of life is still yet to be determined ²⁰. The current hypotheses on the function of sleep include ³⁷:

• Neural maturation
• Facilitation of learning or memory
• Targeted erasure of synapses to “forget” unimportant information that might clutter the synaptic network
• Cognition
• Clearance of metabolic waste products generated by neural activity in the awake brain
• Conservation of metabolic energy.

Wake or Alert Stage

The first stage is the wake stage or stage W, which further depends on whether your eyes are open or closed. During wakefulness, the EEG is characterized by waves of low amplitude and high frequency. This kind of EEG pattern is known as low-voltage fast activity or activated. During eye-open wakefulness, beta waves predominate. Alpha waves (8–13 Hz) become the predominant pattern as you become drowsy and close your eyes, particularly in occipital regions ³⁸. The Electromyography (EMG, a test that measures the electrical activity of muscles) reveals tonic muscle activity with additional phasic activity related to voluntary movements.

EEG recording: beta waves – highest frequency, lowest amplitude (alpha waves are seen during quiet/relaxed wakefulness)

Non-Rapid Eye Movement (NREM) Sleep Stages

• Stage N1 (Light Sleep): This is the transition between wakefulness and sleep, characterized by slowing heart rate and breathing.
• Stage N2 (Intermediate Sleep): Your heart rate and body temperature decrease further, and your body relaxes.
• Stage N3 (Deep Sleep): This is the deepest stage of Non-Rapid Eye Movement (NREM) sleep, when your body performs restorative work, and it is crucial for feeling rested.

Stage 1 or N1 Sleep

NREM Stage 1 (N1) or Light Sleep serves a transitional role in sleep-stage cycling. This is the lightest stage of sleep and begins when more than 50% of the alpha waves are replaced with low-amplitude mixed-frequency (LAMF) activity. Muscle tone is present in the skeletal muscle, and breathing occurs regularly. This stage lasts around 1 to 7 minutes in the initial cycle, comprising 5% of total sleep time and is easily interrupted by a disruptive noise.

Brain activity on the EEG in stage 1 transitions from wakefulness (marked by rhythmic alpha waves) to low-voltage, mixed-frequency waves. Alpha waves are associated with a wakeful relaxation state and are characterized by a frequency of 8 to 13 cycles per second ²⁸.

EEG recording: Theta waves – low voltage.

Stage 2 or N2 Sleep

NREM Stage 2 (N2) represents deeper sleep as the heart rate and body temperature drop ²⁰. The presence of sleep spindles, K-complexes, or both characterizes it ²⁰. Sleep spindles are brief, powerful bursts of neuronal firing in the superior temporal gyri, anterior cingulate, insular cortices, and thalamus, inducing calcium influx into cortical pyramidal cells. This mechanism is believed to be integral to synaptic plasticity. Numerous studies suggest that sleep spindles are essential in memory consolidation, specifically procedural and declarative memory ³⁹. Individuals who learn a new task have a significantly higher density of sleep spindles than those in a control group ⁴⁰.

K-complexes are long delta waves that last approximately one second and are known to be the longest and most distinct of all brain waves. K-complexes are shown to function in maintaining sleep and memory consolidation ⁴¹.

Stage 2 sleep lasts approximately 10 to 25 minutes in the initial cycle and lengthens with each successive cycle, eventually constituting between 45 to 55 percent of the total sleep episode. Stage 2 sleep is when bruxism (teeth grinding) occurs. An individual in stage 2 sleep requires more intense stimuli than in stage 1 to awaken. Brain activity on an EEG shows relatively low-voltage, mixed-frequency activity characterized by the presence of sleep spindles and K-complexes.

EEG recording: Sleep spindles and K complexes.

Stage 3 or N3 Sleep (Deepest Non-REM Sleep)

Sleep stage 3 or N3 sleep is also known as slow-wave sleep (SWS). This is considered the deepest stage of sleep and is characterized by signals with lower frequencies and higher amplitudes, known as delta waves ²⁰. Sleep stage 3 or N3 sleep is the most difficult to awaken from; for some people, loud noises (> 100 decibels) will not lead to an awake state ²⁰. As people age, they spend less time in this slow, delta-wave sleep and more time in stage N2 sleep ²⁰. Although this stage has the greatest arousal threshold, if someone is awoken during this stage, they will have a transient phase of mental fogginess, known as sleep inertia ²⁰. Cognitive testing shows that individuals awakened during this stage tend to have moderately impaired mental performance for 30 minutes to 1 hour ⁴². Sleep stage 3 or N3 sleep stage is when the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. Sleep stage 3 or N3 sleep is also the stage when sleepwalking, night terrors, and bedwetting occur ⁴³.

Sleep stage 3 or N3 sleep lasts only a few minutes and constitutes about 3 to 8 percent of sleep. The EEG shows increased high-voltage, slow-wave activity.

EEG recording: Delta waves – lowest frequency, highest amplitude.

Rapid Eye Movement (REM) Sleep Stage

Rapid eye movement sleep or REM sleep is the fourth and final stage of sleep and is when you have your most vivid and intense dreams. During REM sleep your brain activity increases to near-waking levels, your eyes dart quickly under your eyelids with fluctuating in your breathing and heart rate and most vivid dreams occur in this phase of sleep. Your muscles become limp (atonia) to prevent you from acting out your dreams. EEG recording shows beta waves – similar to brain waves during wakefulness. You experience your first period of REM sleep about 60 to 90 minutes after falling asleep ³⁵.

REM sleep is defined by the presence of desynchronized (low-voltage, mixed-frequency) brain wave activity, muscle atonia, and bursts of rapid eye movements ²⁸. “Sawtooth” wave forms, theta activity (3 to 7 counts per second), and slow alpha activity also characterize REM sleep ²⁶. During the initial cycle, the REM period may last only 1 to 5 minutes; however, it becomes progressively prolonged as the sleep episode progresses ²⁶.

Most adults need about 2 hours of REM sleep each night, which contributes to brain development, brain function, memory consolidation, and emotional health ⁴⁴, ⁴⁵.

Infants and children need more REM sleep, because their brains are still rapidly developing. For example, newborn babies spend around eight hours in REM sleep each day.

How much time you actually spend in REM sleep can vary from night to night. On a night when you’re short of sleep, your total REM time can get cut short. This can trigger your brain to initiate more REM sleep the following night, which is known as a REM rebound ⁴⁶. Some research also suggests that REM sleep may increase after learning new information ⁴⁷.

Because REM sleep enables better brain function, memory, and emotional regulation, a lack of REM sleep can cause a range of issues. On top of that, a lack of REM sleep circumvents healthy sleep overall, contributing to sleep deprivation. In the short term, signs of sleep deprivation can include ⁴⁸:

• Difficulty concentrating
• Excessive daytime sleepiness
• Forgetfulness or poor memory
• Irritability or frustration
• Greater risk of accidents

Over the long term, insufficient sleep can weaken your immune system and raise your risk of conditions like heart disease, diabetes, depression, and anxiety.

How Much Deep Sleep Do I Need?

Different people need different amounts of sleep. Most adults need 7 to 8 hours of sleep a night for good health and mental functioning. Some adults need up to 9 hours a night ⁴⁹. During a healthy night’s sleep for most adults, deep sleep (stage 3 or N3 sleep) makes up between 10% and 20% of total sleeping time ⁵⁰. People who sleep less than approximately 7 hours a night are at a greater risk for heart disease, stroke, asthma, arthritis, depression, and diabetes. Nearly 20% of all car crashes, both fatal and nonfatal, are attributed to drowsy driving. Without enough sleep, your brain may struggle to perform basic functions. You may find it hard to concentrate or remember things. You may become moody and lash out at co-workers or people you love.

If you’re not sure about how much sleep you really need, you can use an online Sleep Calculator (https://www.sleepfoundation.org/sleep-calculator). However, your doctor is in the best position to make a detailed sleep recommendation for you based on your age, your overall health and your unique situation.

Table 1. Recommended Sleep Duration

	Age Range	Recommended Daily Sleep
Infant	4–12 months	12-16 hours (including naps)
Toddler	1–2 years	11-14 hours (including naps)
Preschool	3–5 years	10-13 hours (including naps)
School-age	6-12 years	9-12 hours
Teens	13-18 years	8-10 hours
Adults	18 years and older	7 or more hours

[Source ⁵¹ ]

Just as your brain needs sleep to restore itself, so does your body. When you do not have enough sleep, your risk goes up for several illnesses.

• Diabetes. Your body does not do as well controlling blood sugar when you do not get enough sleep.
• Heart disease. Lack of sleep can lead to high blood pressure and inflammation, two things that can damage your heart.
• Obesity. When you do not get enough rest from sleep, you are more prone to overeat. It is also harder to resist foods high in sugar and fat.
• Infection. Your immune system needs you to sleep so it can fight colds and keep you healthy.
• Mental health. Depression and anxiety often make it hard to sleep. They also can become worse after a string of sleepless nights.

The cancer research branch of the World Health Organization has determined that disruption of regular sleep is “probably carcinogenic to humans”, putting it in the same risk category as the infectious agents malaria and human papillomavirus (HPV), as well as the biochemical weapon mustard gas. Sexual health is affected by sleep deprivation as well, as men with the worst sleeping habits have significantly lower sperm counts, decreased circulating testosterone, and even testicular shrinkage.

Adults generally need about 1.5 to 2 hours of deep sleep per night, which equates to roughly 13-23% of their total recommended sleep time. This stage of sleep is crucial for physical recovery, immune function, and cognitive health, so ensure you are getting sufficient overall sleep and practicing healthy sleep habits to obtain enough deep sleep

Why Deep Sleep is Important?

While all stages of sleep are necessary for good health, deep sleep is important because it is when your body undergoes essential physical restoration, immune system strengthening, and hormone production, while your brain processes and stores memories, consolidates learning, and clears waste products ²³. During deep sleep, your body works to build and repair tissue, muscles, and bones, including by producing high levels of growth hormone ⁵². Achieving sufficient deep sleep helps you wake feeling refreshed, promotes long-term physical and mental health, and supports healthy weight and cardiovascular function ²³. Deep sleep also promotes immune system functioning. Research suggests that it helps you build stronger immune responses and reduce unwanted chronic inflammation ⁵³.

Slow-wave sleep also helps regulate blood sugar levels. As a result, the risk of developing type 2 diabetes may be higher if you don’t get enough deep sleep ⁵⁴. And a shortage of deep sleep has also been linked to high blood pressure ⁵⁵.

Deep sleep is important for cognitive function and memory. Although brain activity slows during deep sleep, this may actually facilitate learning by keeping the brain from becoming oversaturated with information. Evidence suggests that deep sleep also helps eliminate waste material from the brain, which may help protect against dementia ⁵⁶.

Because deep sleep is an essential component of your nightly rest, a shortage of deep sleep contributes to broader impacts of sleep deprivation. In addition to causing tiredness, a shortage of deep sleep can cause general symptoms of sleep deprivation, including ⁵⁷:

• Reduced alertness and attention
• Trouble learning and remembering things
• Irritability
• Symptoms of depression or anxiety
• Increased likelihood of accidents and injuries

On top of these immediate effects, a chronic lack of quality sleep can increase the likelihood of multiple health problems, such as:

• Infections and reduced immune system function
• Obesity
• Type 2 diabetes
• Cardiovascular problems, including high blood pressure, stroke, and heart disease
• Kidney disease

If you want to get more deep sleep, focus on enhancing your overall sleep. If your sleep quality and quantity are good, it usually means you’re getting plenty of restorative deep sleep. You get the most deep sleep during the early part of the night.

One of the most reliable ways to improve your sleep is by practicing good sleep hygiene. Good habits include ⁵⁸:

• Establishing a consistent bedtime and wake-up time
• Ensuring you have a quiet, cool, and dark sleep environment
• Creating a relaxing bedtime routine to wind down in the evening
• Reducing caffeine intake in the afternoon and evening
• Limiting use of mobile devices, tablets, laptops, and other screens for 30 minutes or more before bedtime

There are some additional steps you can try to encourage more deep sleep:

• Take a warm bath: Some research suggests that heating your body with a warm bath before bedtime may induce more slow-wave sleep ⁵⁹. A warm bath raises body temperature, which promotes blood circulation, and the subsequent cooling may help ease the transition to sleep.
• Change your diet: What you eat and drink before bedtime impacts your sleep. One small study found that people eating a diet high in saturated fats obtained less slow-wave sleep ⁶⁰. People who ate more fiber were more likely to have increased amounts of deep sleep.
• Listen to binaural beats: Binaural beats are created by listening to two slightly different tones, one in each ear. The difference between the frequencies of those tones creates a perceived third tone, or binaural beat. Limited research suggests that listening to certain binaural beats may contribute to more stage 3 sleep ⁶¹.

REM sleep behavior disorder causes

In REM sleep behavior disorder (RBD) the nerve pathways in your brain that normally prevent your muscles from moving during normal REM sleep resulting in temporary paralysis of your body no longer work and you may physically act out your dreams. However, the precise neural structures involved in rapid eye movement sleep behavior disorder (RBD) are unknown. Based on animal (cats, rats), lesional, and neuropathologic studies, sleep-regulating nuclei, particularly the pontine tegmentum, are thought to be involved in the pathogenesis of rapid eye movement sleep behavior disorder (RBD). Also, a complex interplay of various neurochemical systems, such as the noradrenergic, cholinergic, and serotonergic systems, seems to exist in the pathogenesis of rapid eye movement sleep behavior disorder (RBD) ⁶², ⁶³.

Normally, generalized atonia of skeletal muscles occurs during REM sleep. This atonia results from active inhibition of the final common pathway of spinal motor neurons by way of the medullary magnocellular reticular formation (MCRF); this suppresses anterior horn cell activity via projections of the ventral lateral reticulospinal tract.

Various pontine nuclei are known to influence the REM and non-REM sleep circuits, including the locus coeruleus (LC), pedunculopontine nucleus (PPN), and laterodorsal tegmental nucleus (LDTN) ⁶⁴. In addition, forebrain cortical and subcortical structures and the substantia nigra, thalamus, hypothalamus, basal forebrain, and frontal cortex are also involved. However, their precise roles are unknown.

Several studies have suggested that idiopathic REM sleep behavior disorder (idiopathic RBD) is a potential marker for the later development of neurodegenerative disorders characterized by alpha-synuclein deposition. These include Parkinson disease, multiple system atrophy, Lewy body dementia and pure autonomic failure, with the risk varying among different studies ⁶², ⁶⁵, ¹³, ⁶⁶, ⁶⁷, ⁶⁸, ⁶⁹, ⁷⁰, ⁷¹, ⁷², ⁷³, ⁷⁴.

Studies have suggested that REM sleep behavior disorder may be associated with alpha-synuclein–mediated degeneration of sleep-regulating nuclei in the brainstem, particularly the pontine tegmentum. In essence, REM sleep behavior disorder may be the prodrome of neurodegenerative disease, such as diffuse Lew body (DLB) disease or Parkinson disease ⁷⁵, ⁶². In experimental studies in cats, bilateral pontine lesions resulted in a persistent absence of REM atonia associated with prominent motor activity during REM sleep similar to that observed in REM sleep behavior disorder in humans.

Studies by Eisensehr et al ⁷⁶ using iodine 123 (123 I) immunoperoxidase technique (IPT) single photon-emission computed tomography (SPECT) scanning demonstrated that striatal presynaptic dopamine transporters are reduced in idiopathic REM sleep behavior disorder.

Studies by Fantini et al ⁷⁷ demonstrated impairment of cortical activity in idiopathic REM sleep behavior disorder, particularly in the occipital region during both wakefulness and REM sleep, compared with controls. Results were similar to those of functional studies, such as of the perfusion and metabolic impairment pattern, observed in diffuse Lew body (DLB) disease and in Parkinson disease. Similar cortical activity in the frontal and temporal regions was impaired only during wakefulness.

Research evidence suggests that many cases of idiopathic REM sleep behavior disorder may not be truly idiopathic, leading some to suggest the term cryptogenic (cause is obscure, hidden, or difficult to identify) rather than idiopathic (unknown cause) ⁷⁸.

In addition, REM sleep behavior disorder may occur in association with various neurologic conditions such as vascular lesions, brainstem neoplasms, demyelinating disease, autoimmune/inflammatory disorders, and neurodegenerative disorders.

Based on findings from sleep studies, most individuals (50%) with initially “idiopathic” REM sleep behavior disorder will eventually develop a neurodegenerative disease. REM sleep behavior disorder is thought to be a prodromal marker of neurodegenerative synucleinopathies and is present in a majority of patients with Parkinson disease (50%), multiple system atrophy (80–90%), dementia with Lewy bodies (80%) ⁷⁹. REM sleep behavior disorder often predates any other sign of these disorders by many years (often more than a decade).

Nightingale et al ⁸⁰ suggested in a study that 36% of persons with narcolepsy experience symptoms of REM sleep behavior disorder. This link led to the identification of a strong association of REM sleep behavior disorder with HLA class II genes ⁸¹, ⁸², ⁸³.

Risk factors for developing REM sleep behavior disorder

Factors associated with the development of REM sleep behavior disorder include:

• Being male and over 50 years old — however, more women are now being diagnosed with the disorder, especially under age 50, and young adults and children can develop the disorder, usually in association with narcolepsy, antidepressant use or brain tumors
• Having a certain type of neurodegenerative disorder, such as Parkinson’s disease, multiple system atrophy, stroke or Lewy bodies dementia
• Having narcolepsy, a chronic sleep disorder characterized by overwhelming daytime drowsiness
• Taking certain medications, especially newer antidepressants, or the use or withdrawal of drugs or alcohol

Recent evidence suggests that there may also be several specific environmental or personal risk factors for REM sleep behavior disorder, including occupational pesticide exposure, farming, smoking or a previous head injury.

REM sleep behavior disorder signs and symptoms

With REM sleep behavior disorder (RBD), instead of experiencing the normal temporary paralysis of your arms and legs (atonia) during REM sleep, you physically act out your dreams. The onset can be gradual or sudden, and episodes may occur occasionally or several times a night. REM sleep behavior disorder (RBD) often worsens with time.

Symptoms of REM sleep behavior disorder (RBD) may include:

• Movement, such as kicking, punching, arm flailing or jumping from bed, in response to action-filled or violent dreams, such as being chased or defending yourself from an attack
• Noises, such as talking, laughing, shouting, emotional outcries or even cursing
• Being able to recall the dream if you awaken during the episode

REM sleep behavior disorder complications

REM sleep behavior disorder complications may include:

• Distress to your sleeping partner or other people living in your home
• Social isolation for fear that others may become aware of your sleep disruption
• Injury to yourself or your sleeping partner

REM sleep behavior disorder diagnosis

To diagnose REM sleep behavior disorder, your doctor reviews your medical history and your symptoms. The most important diagnostic studies in rapid eye movement sleep behavior disorder (REM sleep behavior disorder) include the following:

• Physical and neurological exam. Your doctor will perform a physical and neurological exam and evaluates you for REM sleep behavior disorder and other sleep disorders. REM sleep behavior disorder may have symptoms similar to other sleep disorders, or it may coexist with other sleep disorders such as obstructive sleep apnea (OSA) or narcolepsy.
• Your doctor may ask your sleeping partner whether he or she has ever seen you appear to act out your dreams while sleeping, such as punching, flailing your arms in the air, shouting or screaming. Your doctor may also ask your partner to fill out a questionnaire about your sleep behaviors.
• Nocturnal sleep study (polysomnogram). This is the most important diagnostic test in REM sleep behavior disorder ⁸⁴. Doctors may recommend an overnight study in a sleep lab. During this test, sensors monitor your heart, lung and brain activity, breathing patterns, arm and leg movements, vocalizations, and blood oxygen levels while you sleep. Typically, you’ll be videotaped to document your behavior during REM sleep cycles. On polysomnographic video recording, at least some tonic or phasic abnormalities of muscle tone are observed during REM sleep accompanying the attack, although usually patients have both.
• Monitoring electro-oculogram (EOG)
• Electroencephalogram (EEG) is a test to measure the electrical activity of your brain ⁶⁷, ⁸⁵.
• Electrocardiogram (ECG)
• Multiple electromyography (EMG) channels using chin, bilateral extensor digitorum, and tibialis anterior muscles ⁸⁶

Routine laboratory tests are usually not helpful. Imaging studies are not indicated in idiopathic cases but are indicated if neurologic dysfunction is suggested by history and neurologic examination ¹⁴. Furthermore, a study demonstrated that IPT-SPECT may be a useful tool in the diagnosis of REM sleep behavior disorder ⁸⁷.

REM sleep behavior disorder diagnostic criteria

To diagnose REM sleep behavior disorder (RBD), sleep medicine physicians typically use the symptom criteria from the American Academy of Sleep Medicine’s International Classification of Sleep Disorders Third Edition (ICSD-3), a person must meet these 4 criteria to receive a diagnosis of REM sleep behavior disorder (RBD) ¹⁵:

1. You have repeatedly experienced episodes of acting out your dreams with vocalizations (where you talk, make noises during sleep) or arm and leg movements (such as punching, kicking or running movements) that correspond to what’s taking place in your dream.
2. Episodes occur during REM sleep, as confirmed by an in-laboratory polysomnogram (in-lab sleep study) or your clinical history.
3. Episodes include sleep without atonia, as confirmed by polysomnography.
4. The episodes are not attributed to something else, like another sleep or mental health disorder, a side effect of medication, or substance abuse.

REM sleep behavior disorder can be the first indication of development of a neurodegenerative disease, such as Parkinson’s disease, multiple system atrophy or Lewy body dementia. So if you develop REM sleep behavior disorder, it’s important to follow up with your doctor.

REM sleep behavior disorder DSM-5-TR diagnostic criteria

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) criteria for rapid eye movement sleep behavior disorder are as follows ⁸⁸:

• Recurrent episodes of arousal during sleep associated with vocalization and/or complex motor behaviors that arise during rapid eye movement (REM) sleep
• On waking from these episodes, the individual is not confused or disoriented and is completely alert
• Either of the following is present: REM sleep without atonia on polysomnographic recordings; or a history suggestive of REM sleep behavior disorder and an established synucleinopathy diagnosis (e.g., Parkinson’s disease, multiple system atrophy)
• The episodes cause significant distress or impairment in social, occupational or other areas of functioning which may include serious injury to self or the bed partner
• The disturbance cannot be explained by the effects of a drug of abuse or medication
• The episodes cannot be attributed to another mental disorder or medical condition.

REM sleep behavior disorder differential diagnosis

The following primary disorders of arousal should be considered in the differential diagnosis of rapid eye movement sleep behavior disorder (RBD) ¹³:

• Sleep terrors
• Sleep walking
• Confusional arousals

Secondary disorders of arousal that can be considered in the differential diagnosis of REM sleep behavior disorder include the following:

• Obstructive sleep apnea (OSA) ⁶⁹
• Periodic limb movements in sleep (PLMS)
• Gastroesophageal reflux disease (GERD)
• Nocturnal seizure – eg, frontal lobe epilepsy

Other differentials to consider include the following:

• Posttraumatic stress disorder (PTSD)
• Psychogenic dissociative disease
• Malingering
• Frightening hypnagogic or hypnopompic hallucinations
• Effect of alcohol or drug administration or withdrawal
• Epilepsy in adults with intellectual disability
• Epilepsy in children with intellectual disability
• Absence seizures

REM sleep behavior disorder treatment

The treatment for REM sleep behavior disorder (RBD) is tailored to an individual and can involve a combination of lifestyle changes, medication, and injury prevention techniques.

In 2023, the American Academy of Sleep Medicine (AASM) published guidelines on the management of rapid eye movement sleep behavior disorder (REM sleep behavior disorder) in adults ⁸⁹. All recommendations summarized below are conditional based on the strength of evidence from a systematic review of the literature ⁹⁰.

For adults with idiopathic (isolated) REM sleep behavior disorder, the guidelines suggest the following treatments over no treatment ⁸⁹:

• Clonazepam
• Immediate-release melatonin
• Pramipexole

Transdermal rivastigmine is suggested over no treatment for the management of mild cognitive impairment in adults with idiopathic (isolated) REM sleep behavior disorder ⁸⁹.

For adults with REM sleep behavior disorder due to a medical condition, the guidelines suggest the following treatments over no treatment ⁸⁹:

• Clonazepam
• Immediate-release melatonin

Transdermal rivastigmine is suggested over no treatment for the management of secondary REM sleep behavior disorder in patients with Parkinson disease ⁸⁹.

The guidelines suggest against deep brain stimulation for the treatment of secondary REM sleep behavior disorder due to a medical condition ⁸⁹.

For adults with drug-induced REM sleep behavior disorder, the guidelines suggests discontinuation of the inciting drug ⁸⁹. However, the severity of comorbid conditions for which the inciting drug is taken and the consequences of eliminating treatment must be taken into consideration before drug discontinuation.

Because REM sleep behavior disorder (rapid eye movement sleep behavior disorder) has strong relationships with many neurodegenerative disorders, such as Parkinson disease, multiple system atrophy, and dementia, your neurologist always should explore the possibility of REM sleep behavior disorder in these conditions. REM sleep behavior disorder symptoms may be the first manifestations of these neurodegenerative disorders and may precede the onset of other typical symptoms and signs by several years. Therefore, careful follow-up is needed to assess the risk of neurodegenerative disorder development, for patient counseling, and to plan for potential neuroprotective trials ⁶⁷, ⁶⁹, ⁷⁰, ⁹¹.

Avoiding Triggers

Because the use of certain alcohol or prescription drugs can contribute to REM sleep behavior disorder, making lifestyle changes to reduce or eliminate their use may be part of a person’s treatment. These changes can be part of a larger set of steps to improve sleep hygiene, such as setting a consistent sleep schedule, that normalize sleep and promote sleep quality.

Injury Prevention Techniques

Your doctor may recommend that you make changes in your sleep environment to make it safer for you and your bed partner, including:

• Padding the floor near the bed
• Removing dangerous objects from the bedroom, such as sharp items and weapons
• Placing barriers on the side of the bed
• Moving furniture and clutter away from the bed
• Protecting bedroom windows
• Possibly sleeping in a separate bed or room from your bed partner until symptoms are controlled

REM sleep behavior disorder Medications

REM sleep behavior disorder medications include:

• Melatonin. Your doctor may prescribe a dietary supplement called melatonin, which may help reduce or eliminate your symptoms. Melatonin may be as effective as clonazepam and is usually well-tolerated with few side effects.
• Clonazepam (Klonopin). This prescription medication, often used to treat anxiety, is also the traditional choice for treating REM sleep behavior disorder, appearing to effectively reduce symptoms. Clonazepam may cause side effects such as daytime sleepiness, decreased balance and worsening of sleep apnea.

Melatonin is the preferred, first-line medication for REM sleep behavior disorder. It usually has fewer side effects than other medication options but has similar efficacy ¹⁷. Melatonin is also a safer option for elderly individuals, individuals with dementia, fall risk, or those with sleep apnea. The dosage of melatonin one should take for REM sleep behavior is different than when taking it to fall asleep, and you should consult a sleep physician. The effective dose of melatonin was 3–6 mg taken orally at bedtime. Only 36% of patients experienced adverse effects, which resolved with decreased dosing. Melatonin dosage may be increased every 5–7 days to 12 mg/day in some cases, if tolerated. The mechanism of melatonin is unclear ⁹². Kunz and Bes ⁹³ suggested that melatonin restores REM sleep behavior disorder-related desynchronization of the circadian rhythms. Polysomnographic studies showed possible direct restoration of the mechanisms producing REM sleep muscle atonia.

The prescription drug clonazepam has proven effective in reducing symptoms for 50-80% of individuals with REM sleep disorder ¹⁸. However, it can cause some side effects, including sleepiness, forgetfulness, and impaired balance in the morning. It can also contribute to or worsen sleep apnea ¹⁹. The initial clonazepam dose is 0.5 mg at bedtime. If this is ineffective, clonazepam doses can be increased to 1–2 mg. With continued treatment for years, moderate limb twitching with sleep talking and more complex behaviors may reemerge. Nevertheless, control of the violent behaviors persists. Clonazepam treatment should be continued indefinitely, as violent behaviors and nightmares relapse promptly with discontinuation of medications in almost all patients ⁹⁴.

Other medications, such as tricyclic antidepressants (TCAs), may be effective in some patients with REM sleep behavior disorder. However, tricyclics are also known to actually precipitate REM sleep behavior disorder ⁹⁵. The newer generations of antidepressants, particularly venlafaxine and mirtazapine, are frequent precipitators or aggravators of REM sleep behavior disorder ⁹⁶.

Levodopa may be very effective in patients in whom REM sleep behavior disorder is the harbinger of Parkinson disease ⁹⁴. In addition, anecdotal reports exist of responses to carbamazepine, clonidine, and L-tryptophan in patients with REM sleep behavior disorder ⁹⁴.

Always consult a doctor before taking any prescription or over-the-counter medication. They can best advise you on a treatment plan based on your medical history and symptoms.

Doctors continue to study several other medications that may treat REM sleep behavior disorder. Talk with your doctor to determine the most appropriate treatment option for you.

REM sleep behavior disorder prognosis

The prognosis of REM sleep behavior disorder (rapid eye movement sleep behavior disorder) depends on its cause. In idiopathic cases, the symptoms are controlled with medications. In secondary cases, the prognosis depends on the underlying primary disease. For example, patients with Parkinson disease and REM sleep behavior disorder have poorer cognitive performance and a greater risk of dementia compared to patients with Parkinson disease but without REM sleep behavior disorder ⁷⁹.

No deaths have been reported in idiopathic cases of REM sleep behavior disorder; however, patients and bed partners may experience serious injury ⁹⁵. In the reported cases, 32% of patients had injured themselves and 64% had assaulted their spouse ¹⁴. Subdural hematomas occurred in two patients ¹⁴.

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