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60-576: The newest version of the International Classification of Sleep Disorders (ICSD, 3rd. Ed.) uses State Dissociation as the paradigm for parasomnias. Unlike before, where wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep were considered exclusive states, research has shown that combinations of these states are possible and thus, may result in unusual unstable states that could eventually manifest as parasomnias or as altered levels of awareness. Although

120-418: A PET scan during the night. The PET scan demonstrated a higher blood flow in the hippocampus during SWS/NREM sleep due to the training from the previous day while the control group exhibited no increased blood flow and they had not received the training the prior day. The brain activity during sleep, according to this study, would show the events of the previous day do make a difference. One theory suggests

180-563: A brain disorder that affects cognitive and motor control, have shown considerably different cortical thickening trajectories in contrast with typically developing children per MRI data. Cortical thickness is a common measure of brain maturation; the main difference in children with ADHD shows a delay in cortical thickness, specifically in the frontal lobe. Significant correlations in the trajectory of gray matter thickness and SWA suggest that SWA may be able to indicate levels of cortical maturation on an individual level. However, there has yet to be

240-874: A confused state. It is characterized by the individual's partial awakening and sitting up to look around. They usually remain in bed and then return to sleep. These episodes last anywhere from seconds to minutes and may not be reactive to stimuli. Confusional arousal is more common in children than in adults. It has a lifetime prevalence of 18.5% in children and a lifetime prevalence of 2.9–4.2% in adults. Infants and toddlers usually experience confusional arousals beginning with large amounts of movement and moaning, which can later progress to occasional thrashings or inconsolable crying. In rare cases, confusional arousals can cause injuries and drowsy driving accidents, thus it can also be considered dangerous. Another sleeping disorder may be present triggering these incomplete arousals. Sleep-related abnormal sexual behavior, Sleep sex , or sexsomnia,

300-550: A declarative memory-task; these who had a sleep imbued of NREM stages, had a better performance after the nap or the night, compared to subjects who have been awake or had more REM-sleep. The importance of NREM sleep in memory consolidation has also been demonstrated using cueing; in this paradigm, while participants are sleeping and are in NREM sleep stages, cues are proposed (which can be, for example, aurally-presented sounds or words, odors, and so on). The fact that this procedure

360-471: A good prognosis, since severity decreases with age, the symptoms tend to resolve during puberty. Adults with NREM-related parasomnias, however, are faced with a stronger persistence of the symptoms, therefore, full remission is quite unlikely and is also associated with violent complications, including homicide. The variant sleep-related eating disorders is chronic, without remission, but treatable. REM sleep behavior disorder (RBD) can mostly be handled well with

420-474: A human's during NREM sleep, and the other half of it fully conscious, allowing them to fly while sleeping. Certain species of dolphins also exhibit similar behavior as birds in order to be able to swim while sleeping. In rats , after a 24-hour sleep deprivation, it was found that there was an increase of slow-wave activity in NREM sleep, which corresponds directly with the human brain which when sleep deprived, prioritizes NREM sleep over REM sleep, implying that

480-665: A lifetime prevalence of 7.1% and an annual prevalence of 2.7%. Sleepwalking has a prevalence of 1–17% in childhood, with the most frequent occurrences around the age of eleven to twelve. About 4% of adults experience somnambulism . Normal sleep cycles include states varying from drowsiness all the way to deep sleep. Every time an individual sleeps, he or she goes through various sequences of non-REM and REM sleep. Anxiety and fatigue are often connected with sleepwalking. For adults, alcohol, sedatives, medications, medical conditions and mental disorders are all associated with sleepwalking. Sleep walking may involve sitting up and looking awake when

540-689: A mattress. Besides ensuring the sleep environment is a safe place, pharmacologic therapy using melatonin and clonazepam is also common as a treatment for RBD, even though they might not eliminate all abnormal behaviours. Before starting a treatment with clonazepam, a screening for obstructive sleep apnea should performed. However, clonazepam needs to be manipulated carefully because of its significant side effects, i.e., morning confusion or memory impairment, mainly in patients with neurodegenerative disorders such as dementia . Demographically, 90% of RBD patients are males, and most are older than 50 years of age. However, this prevalence in males could be biased due to

600-428: A model of hippocampal-neocortical dialogue. "Two stages of hippocampal activity have been proposed, the first being the recording of the memory during waking and the second involving the playback of the memory during NREM sleep. This process of reactivation of memory firing sequences is believed to gradually reinforce initially weak connections between neocortical sites allowing the original information to be activated in

660-413: A person is sleeping is to listen to their breathing - once the person falls asleep, their breathing becomes noticeably louder. Not surprisingly, the increased tendency of the upper airway to collapse during breathing in sleep can lead to snoring , a vibration of the tissues in the upper airway. This problem is exacerbated in overweight people when sleeping on the back, as extra fat tissue may weigh down on

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720-447: A person may be able to sleepwalk. According to studies, the mental activity that takes place during NREM sleep is believed to be thought-like, whereas REM sleep includes hallucinatory and bizarre content. NREM sleep is characteristic of dreamer-initiated friendliness, compared to REM sleep where it is more aggressive, implying that NREM is in charge of simulating friendly interactions. The mental activity that occurs in NREM and REM sleep

780-506: A person when awake'. In a minority of cases, hypnogely may be associated with neurological disorders of the central nervous system . Recurrent isolated sleep paralysis is an inability to perform voluntary movements at sleep onset, or upon waking from sleep. Although the affected individual is conscious and recall is present, the person is not able to speak or move. However, respiration remains unimpaired. The episodes last seconds to minutes and diminish spontaneously. The lifetime prevalence

840-435: A physiological activation in which the patient's brain exits from SWS and is caught in between a sleeping and waking state. In particular, these disorders involve activation of the autonomic nervous system , motor system , or cognitive processes during sleep or sleep-wake transitions. Differential diagnosis for NREM-related parasomnias: Confusional arousal is a condition when an individual awakens from sleep and remains in

900-553: A result of a side-effect in prescribed medication —usually antidepressants . Furthermore, substance abuse or withdrawal can result in RBD. Chronic RBD is idiopathic , meaning of unknown origin, or associated with neurological disorders . There is a growing association of chronic RBD with neurodegenerative disorders— Parkinson's disease , multiple system atrophy (MSA), or dementia—as an early indicator of these conditions by as much as 10 years. RBD associated with neurological disorders

960-676: A second. They are also unique to NREM sleep. They appear spontaneously across the early stages, usually in the second stage, much like the sleep spindles. However, unlike sleep spindles, they can be voluntarily induced by transient noises such as a knock at the door. The function of these K-complexes is unknown and further research needs to be conducted. Although study participants' reports of intense dream vividness during REM sleep and increased recollection of dreams occurring during that phase suggest that dreaming most commonly occurs during that stage, dreaming can also occur during NREM sleep, in which dreams tend to be more mundane in comparison. It

1020-458: A sleep diary is helpful to exclude that sleep deprivation could be a precipitating factor. An additional tool could be the partner's log of the events. The following questions should therefore be considered: In potentially harmful or disturbing cases a specialist in sleep disorders should be approached. Video polysomnographic documentation is necessary only in REM sleep behavior disorder (RBD), since it

1080-608: A study where, through electrical stimulations, slow oscillations were induced and boosted; because of this SWA increase, participants had a better performance in declarative memory tasks. Not only SWA helps learning, but it is also crucial, because its suppression has been demonstrated to impair declarative memory consolidation. On the other hand, sleep spindles (especially associated with N2 NREM sleep stage, but can also occur during N3 NREM sleep stage) are also crucial for declarative consolidation; indeed they are enhanced (increasing in density) after declarative learning, their increase

1140-707: A study in which the diagnosis of ADHD can be given directly from SWA readings. Non-rapid eye movement sleep is known for its beneficial effect on memory consolidation , especially for declarative memory (while procedural memory improvement is more associated with REM-sleep), even if establishing a clear-cut distinction between stages' influence on type of learning may not be possible. Generally, both REM and NREM are associated with an increased memory performance, because newly encoded memories are reactivated and consolidated during sleep. NREM sleep has been demonstrated to be intimately correlated with declarative memory consolidation in various studies, where subject slept after

1200-414: Is 7%. Sleep paralysis is associated with sleep-related hallucinations. Predisposing factors for the development of recurrent isolated sleep paralysis are sleep deprivation, an irregular sleep-wake cycle, e.g. caused by shift work, or stress. A possible cause could be the prolongation of REM sleep muscle atonia upon awakening. Nightmares are like dreams primarily associated with REM sleep. Nightmare disorder

1260-436: Is a form of confusional arousal that may overlap with somnambulism. Thereby, a person will engage in sexual acts while still asleep. It can include such acts as masturbation , inappropriate fondling themselves or others, having sex with another person; and in more extreme cases, sexual assault . These behaviors are unconscious, occur frequently without dreaming, and bring along clinical, social, and legal implications. It has

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1320-531: Is a result of two different mind generators, which also explains the difference in mental activity. In addition, there is a parasympathetic dominance during NREM. The reported differences between the REM and NREM activity are believed to arise from differences in the memory stages that occur during the two types of sleep. NREM sleep was divided into four stages in the Rechtschaffen and Kales (R&K) standardization of 1968. That has been reduced to three in

1380-400: Is a test used in the study of sleep; the test result is called a polysomnogram. Below are images of the NREM stages 1, 2 and 3. The figures represent 30-second epochs (30 seconds of data). They represent data from both eyes, EEG, chin, microphone, EKG , legs, nasal/oral air flow, thermistor, thoracic effort, abdominal effort, oximetry , and body position, in that order. EEG is highlighted by

1440-582: Is an essential diagnostic criteria in the ICSD to demonstrate the absence of muscle atonia and to exclude comorbid sleep disorders. For most of the other parasomnias, polysomnographic monitoring is a costly, but still supportive tool in the clinical diagnosis. The use of actigraphy can be promising in the diagnostical assessment of NREM-related parasomnias, for example to rule out sleep deprivation or other sleep disorders, like circadian sleep-wake rhythm disorder which often develops among shift workers. However, there

1500-431: Is associated with a better memory performance (which has been proved using pharmacological manipulation of spindles' density, and measuring outcomes on learning tasks). Schreiner and Rasch (2017) proposed a model illustrating how the cueing beneficial effect on memory during sleep could function, which includes theta and gamma waves and sleep spindles. Increased theta activity represents the successful reestablishment of

1560-498: Is characteristic of NREM dreams, potentially disproving that theory. Research has also shown that dreams during the NREM stage most commonly occur during the morning hours which is also the time period with the highest occurrence of REM sleep. This was found through a study involving subjects taking naps over specific intervals of time and being forcefully awakened, their sleep was separated into naps including only REM sleep and only NREM sleep using polysomnography . This implies that

1620-436: Is conceptualized as a mixture of binge-eating behavior and arousal disorder. Thereby, preferentially high-caloric food is consumed in an uncontrolled manner. However, SRED should not be confused with nocturnal eating syndrome, which is characterized by an excessive consumption of food before or during sleep in full consciousness. Since sleep-related eating disorders are associated with other sleep disorders, successful treatment of

1680-405: Is considered fairly common. Sleep talking is associated with REM-related parasomnias as well as with disorders or arousal. It occurs in all sleep states. As yet, there is no specific treatment for sleeptalking available. Parasomnias are most commonly diagnosed by means of questionnaires. These questionnaires include a detailed analyses of the clinical history and contain questions to: Furthermore,

1740-536: Is currently no generally accepted standardized technique available of identifying and quantifying periodic limb movements in sleep (PLMS) that distinguishes movements resulting from parasomnias, nocturnal seizures, and other dyskinesias. Eventually, using actigraphy for parasomnias in general is disputed. Parasomnias can be considered as potentially harmful to oneself as well as to bed partners, and are associated with other disorders. Children with parasomnias do not undergo medical intervention, because they tend to recover

1800-544: Is defined as recurrent nightmares associated with awakening dysphoria that impairs sleep or daytime functioning. It is rare in children, however persists until adulthood. About 2/3 of the adult population report experiencing nightmares at least once in their life. Before the ICSD-3, catathrenia was classified as a rapid-eye-movement sleep parasomnia, but is now classified as sleep-related breathing disorder. The painful penile erections will appear only during sleep. This condition

1860-610: Is frequently related to abnormal accumulation of alpha-synuclein , and more than 80% of patients with idiopathic RBD might develop Lewy body disease (LBD). The diagnosis is based on clinical history, including partner's account and needs to be confirmed by polysomnography (PSG), mainly for its accuracy in differentiating RBD from other sleep disorders, since there is a loss of REM atonia with excessive muscle tone. However, screening questionnaires, such as RBDSQ , are also very useful for diagnosing RBD. A similar phenomenon to somniloquy named hypnogely has been observed, characterised by

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1920-415: Is known about NREM, so scientists have conducted studies in other animals to potentially understand more, in particular why the brain has evolved to have two distinct states. In their studies, it was found that between birds and certain mammals like dolphins , their brains exhibit similar behavior. It was found that certain species of birds have half their brain's hemisphere release brain waves similar to

1980-401: Is not included. There are distinct electroencephalographic and other characteristics seen in each stage. Unlike REM sleep, there is usually little or no eye movement during these stages. Dreaming occurs during both sleep states, and muscles are not paralyzed as in REM sleep. People who do not go through the sleeping stages properly get stuck in NREM sleep, and because muscles are not paralyzed

2040-653: Is present during REM sleep. Sexual activity does not produce any pain. There is no lesion or physical damage, but hypertonia of the pelvic floor could be one cause. It affects men of all ages, but especially from middle-age onward. Several pharmacologic treatments such as propranolol, clozapine, clonazepam, baclofen and various antidepressants are considered effective. Sleep-related hallucinations are brief episodes of dream-like imagery that can be of any sensory modality, i.e., auditory, visual, or tactile. They are differentiated between hypnagogic hallucination , that occur at sleep onset, and hypnapompic hallucinations , which occur at

2100-425: Is somewhat impaired for periods up to 30 minutes or so, relative to awakenings from other stages. This phenomenon has been called " sleep inertia ." After sleep deprivation there is usually a sharp rebound of SWS, suggesting there is a "need" for this stage. Slow Wave Sleep (SWS) is a highly active state unlike a state of brain quiescence as previously thought. Brain imaging data has shown that during NREM sleep

2160-484: Is suggested that dreaming involves two selfs: aggressive self (REM) and friendly self (NREM). It seems that in NREM dreams, the self is put in different situations, largely negative, but is found to respond in a way that befriends or embraces the unfamiliar. It is sometimes thought that in NREM sleep, the dreamers are "aware of being aware", also known as "secondary awareness", which allows them to make better decisions and potentially reflect on them. During non-REM sleep,

2220-472: Is understood as memories and learned skills being metabolized during NREM sleep; the decrease in SWA is considered a reflection of synaptic rewiring and, therefore, an effect of behavioral maturation concluding. The critical period from childhood to emerging adulthood is also considered a sensitive period for mental disorders to manifest. For example, children with attention deficit hyperactivity disorder (ADHD),

2280-413: The cortex independently of the hippocampus, and thus ensuring refreshed encoding capacity of the hippocampus." Maquet concluded that the areas of the brain involved with information processing and memory have increased brain activity during the slow wave sleep period. Events experienced in the previous day have more efficient and clearer memory recall the next day thus indicating that the memory regions of

2340-464: The 2007 update by The American Academy of Sleep Medicine (AASM). Sleep spindles are unique to NREM sleep. The most spindle activity occurs at the beginning and the end of NREM. Sleep spindles involve activation in the brain in the areas of the thalamus, anterior cingulate and insular cortices, and the superior temporal gyri. They have different lengths. There are slow spindles in the range of 11 – 13 Hz that are associated with increased activity in

2400-709: The NREM-related disorder with the process of growth. In those cases, the parents receive education on sleep hygiene to reduce and eventually eliminate precipitating factors. In adults psychoeducation about a proper sleep hygiene can reduce the risk to develop parasomnia. Case studies have shown that pharmacological interventions can improve symptoms of parasomnia, however mostly they are accompanied by side-effects. Behavioral treatments, i.e., relaxation therapy, biofeedback, hypnosis, and stress reduction, may also be helpful, but are not considered as universally effective. NREM-related parasomnias which are common in childhood show

2460-441: The airway, closing it. This can lead to sleep apnea . The occurrence of parasomnias is very common in the last stage of NREM sleep. Parasomnias are sleep behaviors that affect the function, quality, or timing of sleep, caused by a physiological activation in which the brain is caught between the stages of falling asleep and waking. The autonomous nervous system, cognitive process, and motor system are activated during sleep or while

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2520-632: The brain are activated during SWS/NREM sleep instead of being dormant as previously thought. NREM SWS, also known as slow wave activity (SWA), is regarded as highly important in brain development due not only to its homeostatic behavior but also because of its distinct correlation with age. Children sleep longer and deeper than adults. The difference in depth of sleep has been quantified by EEG recordings of SWA. An increase in SWA peaks just before puberty and exponentially decreases from adolescence to adulthood in both longitudinal and cross-sectional studies of typically developing participants. This phenomenon

2580-528: The fact that women tend to have a less violent type of RBD, which leads to lower reports at sleep centres and different clinical characteristics. While men might have more aggressive behaviour during dreaming, women have presented more disturbance in their sleep. RBD may be also influenced by a genetic compound, since primary relatives seem to have significantly more chance to develop RBD compared with non-relatives control group. Typical clinical features of REM sleep behavior disorder are: Acute RBD occurs mostly as

2640-603: The individual are futile and may prolong or intensify their confused state. Usually they experience amnesia after the event but it may not be complete amnesia. Up to 3% of adults have sleep terrors and exhibited behavior of this parasomnia can range from mild to extremely violent. This is very prevalent in those who have violent post-traumatic stress disorder (PTSD). They typically occur in stage 3 sleep. The Diagnostic and Statistical Manual of Mental Disorders (DSM-V) classifies sleep-related eating disorder (SRED) under sleepwalking, while ICSD classifies it as NREM-related parasomnia. It

2700-466: The individual is actually asleep, and getting up and walking around, moving items or undressing themselves. They will also be confused when waking up or opening their eyes during sleep. Sleep walking can be associated with sleeptalking. Sleep terror is the most disruptive arousal disorder since it may involve loud screams and panic; in extreme cases, it may result in bodily harm or property damage by running about or hitting walls. All attempts to console

2760-484: The latter can reduce symptoms of this parasomnia. Unlike other parasomnias, rapid eye movement sleep behavior disorder (RBD) in which muscle atonia is absent is most common in older adults. This allows the individual to act out their dreams and may result in repeated injury — bruises , lacerations , and fractures —to themselves or others. Patients may take self-protection measures by tethering themselves to bed, using pillow barricades , or sleeping in an empty room on

2820-468: The memory after the cueing: if such an increase is observed, it means that the association between the cue and the memory trace is strong enough, and that the cue is presented in an effective way and time. Theta waves interacts with gamma activity, and - during NREM - this oscillatory theta-gamma produces the relocation of the memory representation, from the hippocampus to the cortex. On the other hand, sleep spindles increase occurs right after or in parallel to

2880-562: The person wakes up from sleep. Some examples of parasomnias are somnambulism (sleep walking), somniloquy (sleep talking), sleep eating , nightmares or night terrors , sleep paralysis , and sexsomnia (or " sleep sex "). Many of these have a genetic component, and can be quite damaging to the person with the behavior or their bed partner. Parasomnias are most common in children, but most children have been found to outgrow them with age. However, if not outgrown, they can cause other serious problems with everyday life. Polysomnography (PSG)

2940-416: The polysomnographic occurrence of REM sleep is not required for dreaming. Rather, the actual mechanisms that create REM sleep cause changes to one's sleep experience. Through these changes, by morning, a sub-cortical activation occurs during NREM that is comparable to the type that occurs during REM. It is this sub-cortical activation that results in dreaming during the NREM stage during the morning hours. It

3000-523: The previous definition is technically correct, it contains flaws. The consideration of the State Dissociation paradigm facilitates the understanding of the sleep disorder and provides a classification of 10 core categories. NREM parasomnias are arousal disorders that occur during stage 3 (or 4 by the R&;K standardization ) of NREM sleep—also known as slow wave sleep (SWS). They are caused by

3060-566: The red box. Sleep spindles in the stage 2 figure are underlined in red. Stage N1: [REDACTED] Stage N2: [REDACTED] Stage N3: [REDACTED] Slow-wave sleep (SWS) is made up of the deepest stage of NREM, and is often referred to as deep sleep. The highest arousal thresholds (e.g. difficulty of awakening, such as by a sound of a particular volume) are observed in stage 3. A person will typically feel groggy when awakened from this stage, and indeed, cognitive tests administered after awakening from stage 3 indicate that mental performance

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3120-491: The regional brain activity is influenced by the waking experience just passed. A study was done involving an experimental and a control group to have them learn to navigate a 3D maze. The blood flow in the parahippocampal gyrus increased in conjunction with the individual's performance through the 3D maze. Participants were then trained in the maze for 4 hours and later, during the various sleep cycles of NREM sleep, REM sleep and wakefulness, they were scanned twelve times using

3180-418: The sleeper spontaneously laughing . This phenomenon appears to be fairly common. In a majority of cases, hypnogely is a genuine behavioural response and benign physiological phenomenon that occurs while the sleeper is dreaming in REM sleep. The laughter exhibited by subjects experiencing hypnogely isn't always connected with the subject of the dream; 'Typically, these dreams are odd, bizarre or even unfunny for

3240-410: The superior frontal gyrus, and fast spindles in the range of 13 – 15 Hz that are associated with recruitment of sensorimotor processing cortical regions, as well as recruitment of the mesial frontal cortex and hippocampus. There is no clear answer as to what these sleep spindles mean, but ongoing research hopes to illuminate their function. K-complexes are single long delta waves that last for only

3300-517: The theta augmentation, and is a necessary mechanism for the stabilization, the reinforcement and also the integration of the newly encoded memory trace. Importantly, in this working model, slow oscillations have the role of a 'time-giving pace maker', and seem to be a prerequisite for the success of cueing. According to this model, enhancing only slow waves or only spindles, is not sufficient to improve memory function of sleep: both need to be increased to obtain an influence and this latter. Not much

3360-460: The tonic drive to most respiratory muscles of the upper airway is inhibited. This has two consequences: However, because the diaphragm is largely driven by the autonomous system, it is relatively spared of non-REM inhibition. As such, the suction pressures it generates stay the same. This narrows the upper airway during sleep, increasing resistance and making airflow through the upper airway turbulent and noisy. For example, one way to determine whether

3420-412: The transition of sleep to awakening. Although normal individuals have reported nocturnal hallucinations, they are more frequent in comorbidity with other sleep disorders, e.g. narcolepsy. According to ICSD-3 it is not defined a disorder in particular. It is rather an isolated symptom or normal variant and ranges from isolated speech to full conversations without recall. With a lifetime prevalence of 69% it

3480-628: The use of melatonin or clonazepam. However, there is high comorbidity with neurodegenerative disorders, that is in up to 93% of cases. The underlying psychopathology of nightmare disorder complicates a clear prognosis. The prognosis for other parasomnias seems promising. While exploding head syndrome usually resolves spontaneously, the symptoms for sleep-related hallucinations tend to diminish over time. Non-rapid eye movement sleep Non-rapid eye movement sleep ( NREM ), also known as quiescent sleep , is, collectively, sleep stages 1–3, previously known as stages 1–4. Rapid eye movement sleep (REM)

3540-458: Was effective on the improvement of the later memory performance, indicates that during these stages, there is a reactivation of the memory traces and a subsequent consolidation, which are facilitated by the cues; importantly, this does not work if the cueing is presented when subjects are awake or in REM stages. Furthermore, the specific and crucial role of SWS (Slow-Wave Sleep, a stage of NREM sleep) in memory consolidation has been demonstrated in

3600-471: Was initially thought that NREM sleep is the absence of dreaming, or dreams occur more rarely compared to REM sleep because 90–95% of those who wake up in the middle of REM sleep will report that they have had a dream, but only 5–10% of those waking up in the middle of non-REM sleep will report they've had a dream. However, when asked for more general thought processes or feelings, 70% of people who awaken from NREM sleep reports of having dream-like feelings, which

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