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105-431: A dakimakura ( 抱き枕 ; from daki 抱き "embrace" and makura 枕 "pillow") is a type of large pillow from Japan which is usually coupled with pillow covers depicting anime characters. The word is often translated to English as body pillow , waifu pillow , or husbando pillow . Dakimakura are similar to Western orthopedic body pillows , and are commonly used by Japanese youth as " comfort objects ". During

210-768: A REM rebound , which refers to an increase in the time spent in REM stage over normal levels. These findings are consistent with the idea that REM sleep is biologically necessary. However, the "rebound" REM sleep usually does not last fully as long as the estimated length of the missed REM periods. After the deprivation is complete, mild psychological disturbances, such as anxiety , irritability , hallucinations , and difficulty concentrating may develop and appetite may increase. There are also positive consequences of REM deprivation. Some symptoms of depression are found to be suppressed by REM deprivation; aggression may increase, and eating behavior may get disrupted. Higher norepinepherine

315-629: A sham which is closed on all sides and usually has a slit in the back through which the pillow is placed. Rectangular standard bed pillow cases usually do not have zippers, but instead, have one side open all the time. Often, a zippered pillow protector is placed around standard pillows with the case in turn covering the protector. Fillers are chosen on the basis of comfort, resilience, thermal properties, cost and also for medical and ethical reasons. The most common synthetic fillers are materials derived from polymer fibers, such as polyester and memory foam . Synthetic fillers in general are inexpensive and in

420-539: A 24-hour day in REM sleep. Sleeping reptiles do not seem to have PGO waves or the localized brain activation seen in mammalian REM. However, they do exhibit sleep cycles with phases of REM-like electrical activity measurable by EEG. A recent study found periodic eye movements in the central bearded dragon of Australia, leading its authors to speculate that the common ancestor of amniotes may therefore have manifested some precursor to REMS. Observations of jumping spiders in their nocturnal resting position also suggest

525-520: A 5cm-10cm valance round all four sides. With a hemstitched or corded decoration around the inner edge of the valance." The opening/closure of pillow cases ranges from the straightforward "bag style" common in the United States to the "housewife style" more common in Europe, with a pocket inside the open end to fully contain the pillow. "Housewife is ... essentially a bag, with a flap in the open end to tuck

630-500: A REM sleep-like state characterized by bouts of twitching and retinal movements and hints of muscle atonia (legs curling up as a result of pressure loss caused by muscle atonia in the prosoma). Sleep deprivation experiments on non-human animals can be set up differently than those on humans. The "flower pot" method involves placing a laboratory animal above water on a platform so small that it falls off upon losing muscle tone. The naturally rude awakening which results may elicit changes in

735-569: A boyfriend pillow) is a large, high-backed pillow with two "arms." It is used to prop the user upright while in bed or on the floor, as for reading or watching television . Because of this common use, a husband pillow is also called a reading pillow. A pillow fight is a common game mostly played by young children (but also by teens and adults) in which they engage in mock physical conflict, using pillows as weapons. Pillow fights are known to occasionally occur during children's sleepovers. Since pillows are usually soft, injuries rarely occur. The heft of

840-510: A complex brain process such as REM sleep indicates that it serves an important function for the survival of mammalian and avian species. It fulfills important physiological needs vital for survival to the extent that prolonged REM sleep deprivation leads to death in experimental animals. In both humans and experimental animals, REM sleep loss leads to several behavioral and physiological abnormalities. Loss of REM sleep has been noticed during various natural and experimental infections. Survivability of

945-404: A drug-free baseline week, 19 days on either paroxetine or fluvoxamine with morning and evening doses, and 5 days of absolute discontinuation. Results showed that SSRI treatment decreased the average amount of dream recall frequency in comparison to baseline measurements as a result of serotonergic REM suppression. Fluvoxamine increased the length of dream reporting, bizarreness of dreams as well as

1050-431: A dual purpose. They often have fancy cover material which serves to decorate the room where they are found. Since decorative textiles are commonly 54 inches in width, many decorative pillows finish about 17x17 inches. (54/3 = 18, less seam allowance) When used to decorate a fully made up bed, decorative pillows are likely thrown aside at bedtime, since they are not covered with a washable pillow case, thus, while found on

1155-425: A form of bedding that supports the head and neck. Other types of pillows are designed to support the body when lying down or sitting. There are also pillows that consider human body shape for increased comfort during sleep. Decorative pillows used on beds, couches or chairs are sometimes referred to as cushions . In contemporary western culture, pillows consist of a plain or patterned fabric envelope (known as

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1260-412: A handy decorative pillow for lumbar support, as needed, while seated on a sofa. Likewise, for the occasional nap, decorative pillows are handy for supporting the head or neck, even though they may not be covered with a pillow case, as are bed pillows. There are five common synonyms for decorative pillows which are descriptive of their use in the home. "Accent" pillows emphasize or accent some other part of

1365-493: A higher proportion of REM sleep. The transition to REM sleep brings marked physical changes, beginning with electrical bursts called "ponto-geniculo-occipital waves" ( PGO waves ) originating in the brain stem . REM sleep occurs 4 times in a 7-hour sleep. Organisms in REM sleep suspend central homeostasis , allowing large fluctuations in respiration , thermoregulation and circulation which do not occur in any other modes of sleeping or waking. The body abruptly loses muscle tone,

1470-616: A human was considered to be the essence of life and sacred. The Romans and Greeks of ancient Europe mastered the creation of the softer type pillow. These pillows were stuffed with reeds , feathers , and straw in order to make them softer and more comfortable. Only upper-class people typically owned these softer pillows; however, all classes of people were allowed to use some type of pillow while sleeping, lying down or sitting in order to give them support. People in ancient Europe started to use pillows when going to church in order to kneel on while praying and to place holy books on. This

1575-410: A modest REM rebound . Techniques of neurosurgery , chemical injection, electroencephalography , positron emission tomography , and reports of dreamers upon waking have all been used to study this phase of sleep. REM sleep is called "paradoxical" because of its similarities to wakefulness . Although the body is paralyzed, the brain acts as if it is somewhat awake, with cerebral neurons firing with

1680-635: A nearly complete absence of monoamine neurotransmitters histamine, serotonin and norepinephrine . Experiences of REM sleep are not transferred to permanent memory due to absence of norepinephrine. REM sleep is physiologically different from the other phases of sleep, which are collectively referred to as non-REM sleep (NREM sleep, NREMS, synchronized sleep). The absence of visual and auditory stimulation ( sensory deprivation ) during REM sleep can cause hallucinations . REM and non-REM sleep alternate within one sleep cycle, which lasts about 90 minutes in adult humans. As sleep cycles continue, they shift towards

1785-410: A night using specifically selected ironwood pillows, sturdy pillows enabled great apes to escape being hunted by night predators and not fall out of the trees while asleep. It is likely that this was necessitated by the evolution of large, energy-consuming brains. Though it may also have led to longer periods of REM sleep , that in turn increased their cognitive capacity. The earliest recorded use of

1890-460: A night's sleep. The first REM episode occurs about 70 minutes after falling asleep. Cycles of about 90 minutes each follow, with each cycle including a larger proportion of REM sleep. (The increased REM sleep later in the night is connected with the circadian rhythm and occurs even in people who did not sleep in the first part of the night.) In the weeks after a human baby is born, as its nervous system matures, neural patterns in sleep begin to show

1995-549: A pillow can still knock a young person off balance, especially on a soft surface such as a bed, which is a common venue. In earlier eras, pillows would often break, shedding feathers throughout a room. Modern pillows tend to be stronger and are often filled with a solid block of artificial filling, so breakage occurs far less frequently. Pillow talk refers to the relaxed, intimate conversation that often occurs between two sexual partners after sexual activity , usually accompanied by cuddling, caresses, and other physical intimacy . It

2100-432: A pillowcase) which contains a soft stuffing, typically synthetic and typically standardized in sizes and shape. Pillows have been historically made of a variety of natural materials and many cultures continue to use pillows made from natural materials in the world. The word pillow comes from Middle English pilwe , from Old English pyle (akin to Old High German pfuliwi ) and from Latin pulvinus . The first known use of

2205-505: A rhythm of REM and non-REM sleep. (In faster-developing mammals, this process occurs in utero.) Infants spend more time in REM sleep than adults. The proportion of REM sleep then decreases significantly in childhood. Older people tend to sleep less overall, but sleep in REM for about the same absolute time (and therefore spend a greater proportion of sleep in REM). Rapid eye movement sleep can be subclassified into tonic and phasic modes. Tonic REM

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2310-492: A room or lounge area. Tent-flap pillows are placed at the front of a stack of pillows decorating a bed. This pillows have a separate flap of fabric that is attached at the top of the pillow and folds down over the face. The tent flap can be loose or tacked down; if the flap is loose a decorative tassel or bead is usually used to weigh the flap down so it hangs properly. Floor pillows are another subset of decorative pillows. These pillows often finish 26×26 inches (one half of

2415-568: A sex pillow is to place it under the receiving partner's buttocks or hips before assuming the missionary position ; this pivots the pelvis and increases depth of penetration. A pillow menu is a list of available pillows provided by a hotel to guests, usually free of charge. It allows guests to make an alternative pillow choice. Some common pillow alternatives are memory foam , buckwheat hull, and hypoallergenic . Some hotels offer pillows to treat specific conditions such as headaches or stress . Rapid eye movement sleep The REM phase

2520-448: A shift of gaze in dream imagery. Against this hypothesis is that such eye movements occur in those born blind and in fetuses in spite of lack of vision. Also, binocular REMs are non-conjugated (i.e., the two eyes do not point in the same direction at a time) and so lack a fixation point . In support of this theory, research finds that in goal-oriented dreams, eye gaze is directed towards the dream action, determined from correlations in

2625-404: A shrapnel injury to the brainstem did not find the individual's memory to be impaired. Antidepressants, which suppress REM sleep, show no evidence of impairing memory and may improve it. Graeme Mitchison and Francis Crick proposed in 1983 that by virtue of its inherent spontaneous activity, the function of REM sleep "is to remove certain undesirable modes of interaction in networks of cells in

2730-466: A state known as REM atonia. In 1953, Professor Nathaniel Kleitman and his student Eugene Aserinsky defined rapid eye movement and linked it to dreams. REM sleep was further described by researchers, including William Dement and Michel Jouvet . Many experiments have involved awakening test subjects whenever they begin to enter the REM phase, thereby producing a state known as REM deprivation. Subjects allowed to sleep normally again usually experience

2835-477: A thinner and softer pillow for sleeping face down, medium support for sleeping on one's back, and a thicker and firmer pillow for sleeping on the side. The classic bed pillow shape is usually a square or rectangle. In the US, they are common in these three sizes (in inches): Standard (20×26 inches), Queen (20×30 inches), and King (20×36 inches). In the US, a less common size is Jumbo (20×28 inches), which

2940-532: Is 11–40% lower. Neural activity during REM sleep seems to originate in the brain stem , especially the pontine tegmentum and locus coeruleus . REM sleep is punctuated and immediately preceded by PGO (ponto-geniculo-occipital) waves , bursts of electrical activity originating in the brain stem. (PGO waves have long been measured directly in cats but not in humans because of constraints on experimentation; however, comparable effects have been observed in humans during "phasic" events which occur during REM sleep, and

3045-678: Is a possible cause of these results. Whether and how long-term REM deprivation has psychological effects remains a matter of controversy. Several reports have indicated that REM deprivation increases aggression and sexual behavior in laboratory test animals. Rats deprived of paradoxical sleep die in 4–6 weeks (twice the time before death in case of total sleep deprivation). Mean body temperature falls continually during this period. It has been suggested that acute REM sleep deprivation can improve certain types of depression —when depression appears to be related to an imbalance of certain neurotransmitters. Although sleep deprivation in general annoys most of

3150-486: Is a tradition that still lives on today. In addition, the Romans and Greeks used their pillows by placing them under the head of those deceased just like the ancient Egyptians did. Chinese pillows were traditionally solid, though sometimes used with a softer fabric over them. Over many Chinese dynasties, pillows were made from a wide range of materials including bamboo, jade, porcelain, wood, and bronze. Ceramic pillows became

3255-795: Is also active during REM sleep and may participate in generating the PGO waves, and experimental suppression of the amygdala results in less REM sleep. The amygdala may also regulate cardiac function in lieu of the less active insular cortex . Compared to slow-wave sleep , both waking and paradoxical sleep involve higher use of the neurotransmitter acetylcholine , which may cause the faster brainwaves. The monoamine neurotransmitters norepinephrine , serotonin and histamine are completely unavailable. Injections of acetylcholinesterase inhibitor , which effectively increases available acetylcholine, have been found to induce paradoxical sleep in humans and other animals already in slow-wave sleep. Carbachol , which mimics

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3360-414: Is also known as paradoxical sleep ( PS ) and sometimes desynchronized sleep or dreamy sleep , because of physiological similarities to waking states including rapid, low-voltage desynchronized brain waves . Electrical and chemical activity regulating this phase seem to originate in the brain stem , and is characterized most notably by an abundance of the neurotransmitter acetylcholine , combined with

3465-465: Is associated with honesty, sexual afterglow, and bonding . In the Western world there are many cultural references to pillow talk. Chinese rock pillows ( simplified Chinese : 石头枕头 ; traditional Chinese : 石頭枕頭 ; pinyin : shítou zhěntou ) played an important role in ancient China. Made from jade , they were believed to translate the energy from the stone to the human brain. Originating in

3570-532: Is characterized by theta rhythms in the brain; phasic REM is characterized by PGO waves and actual "rapid" eye movements. Processing of external stimuli is heavily inhibited during phasic REM, and recent evidence suggests that sleepers are more difficult to arouse from phasic REM than in slow-wave sleep. Selective REMS deprivation causes a significant increase in the number of attempts to go into REM stage while asleep. On recovery nights, an individual will usually move to stage 3 and REM sleep more quickly and experience

3675-452: Is designed to provide support and comfort to the body and head. There are three main types of pillows; bed pillows, orthopedic pillows and decorative pillows, with some overlapping of use between these. The appropriate size of a bed pillow depends on the size of the bed. Larger pillows than standard are available for queen- and king-sized beds. The choice of bed pillow depends to some extent upon sleeping positions: one manufacturer recommends

3780-517: Is larger than the Standard Size but smaller than the Queen Size. Pillows are generally covered with a removable pillow case, which facilitates laundering. Apart from the color and from the material of which they are made, pillowcases have three contrasting characteristics: Size conforms to the pillow the case is to contain. They are typically described as: Square is also called continental in

3885-784: Is not well regulated during REM sleep, and thus organisms become more sensitive to temperatures outside their thermoneutral zone . Cats and other small furry mammals will shiver and breathe faster to regulate temperature during NREMS—but not during REMS. With the loss of muscle tone, animals lose the ability to regulate temperature through body movement. (However, even cats with pontine lesions preventing muscle atonia during REM did not regulate their temperature by shivering.) Neurons that typically activate in response to cold temperatures—triggers for neural thermoregulation—simply do not fire during REM sleep, as they do in NREM sleep and waking. Consequently, hot or cold environmental temperatures can reduce

3990-457: Is that the PGO electrical waves, which precede the eye movements, also influence memory. REM sleep could provide a unique opportunity for "unlearning" to occur in the basic neural networks involved in homeostasis, which are protected from this "synaptic downscaling" effect during deep sleep. REM sleep prevails most after birth, and diminishes with age. According to the "ontogenetic hypothesis", REM (also known in neonates as active sleep ) aids

4095-692: Is the Dakimakura , a kind of "hugging pillow" originating in Japan that have been endowed with anthropomorphic and zoomorphic qualities and pop culture references for additional psychological comfort. Other types of hugging pillows are more practical, such as the Guling , long hugging pillow originating from Indonesia and the Abrazador , a long hugging pillow originating from the Philippines . A husband pillow (also known as

4200-524: The Ming dynasty , this piece of material was trusted to cure headaches or depression, or simply to better the intelligence of those who use it. It was more common among royalty because it was expensive and rare. Families often married off children based on the quality and intricacy of these pillows. Today, rock pillows are still commonly used during the hot summer months in China. Cushioning designed for specific parts of

4305-460: The Song , Jin , and Yuan dynasties between the 10th and 14th century, but slowly phased out during the Ming and Qing dynasties between 1368 and 1911 with the emergence of better pillow making materials. Pillows consist of a filler material enclosed in a fabric cover or shell. Covers are made of cloth , such as silk , known as the pillow case or pillow slip. Some pillows have a fancier cover called

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4410-424: The cortex ; patterns of EEG activity similar to these rhythms are also observed during wakefulness. The cortical and thalamic neurons in the waking and REM sleeping brain are more depolarized (fire more readily) than in the NREM deep sleeping brain. Human theta wave activity predominates during REM sleep in both the hippocampus and the cortex. During REM sleep, electrical connectivity among different parts of

4515-418: The developing brain by providing the neural stimulation that newborns need to form mature neural connections. Sleep deprivation studies have shown that deprivation early in life can result in behavioral problems, permanent sleep disruption, and decreased brain mass. The strongest evidence for the ontogenetic hypothesis comes from experiments on REM deprivation, and from the development of the visual system in

4620-440: The dual-process hypothesis of sleep and memory, the two major phases of sleep correspond to different types of memory. "Night half" studies have tested this hypothesis with memory tasks either begun before sleep and assessed in the middle of the night, or begun in the middle of the night and assessed in the morning. Slow-wave sleep , part of non-REM sleep, appears to be important for declarative memory . Artificial enhancement of

4725-414: The lateral geniculate nucleus and primary visual cortex . Ioannis Tsoukalas of Stockholm University has hypothesized that REM sleep is an evolutionary transformation of a well-known defensive mechanism, the tonic immobility reflex. This reflex, also known as animal hypnosis or death feigning, functions as the last line of defense against an attacking predator and consists of the total immobilization of

4830-472: The neocortex , while lower levels of acetylcholine and norepinephrine in the neocortex encourage the uncontrolled spread of associational activity within neocortical areas. This is in contrast to waking consciousness, where higher levels of norepinephrine and acetylcholine inhibit recurrent connections in the neocortex. REM sleep through this process adds creativity by allowing "neocortical structures to reorganise associative hierarchies, in which information from

4935-504: The 1990s using positron emission tomography (PET) confirmed the role of the brain stem and suggested that, within the forebrain , the limbic and paralimbic systems showed more activation than other areas. The areas activated during REM sleep are approximately inverse to those activated during non-REM sleep and display greater activity than in quiet waking. The "anterior paralimbic REM activation area" (APRA) includes areas linked with emotion , memory, fear and sex, and may thus relate to

5040-591: The 5 most popular sizes are: 180x60, 170x60, 160x60, 150x50 and 140x40 cm. Love pillows are a subset of dakimakura usually portraying life-size pictures of characters in intercourse poses. They may portray anime characters, furry characters, or pornographic film actors . Pillow A pillow is a support of the body at rest for comfort , therapy , or decoration. Pillows are used in different variations by many species, including humans . Some types of pillows include throw pillows, body pillows, decorative pillows, and many more. Pillows that aid sleeping are

5145-455: The ED is from a psychological rather than a physiological cause. In females, erection of the clitoris ( nocturnal clitoral tumescence or NCT) causes enlargement, with accompanying vaginal blood flow and transudation (i.e. lubrication). During a normal night of sleep, the penis and clitoris may be erect for a total time of from one hour to as long as three and a half hours during REM. Body temperature

5250-517: The REM-on neurons. McCarley and Hobson suggested that the REM-on neurons actually stimulate REM-off neurons, thereby serving as the mechanism for the cycling between REM and non-REM sleep. They used Lotka–Volterra equations to describe this cyclical inverse relationship. Kayuza Sakai and Michel Jouvet advanced a similar model in 1981. Whereas acetylcholine manifests in the cortex equally during wakefulness and REM, it appears in higher concentrations in

5355-482: The UK. German pillow sizes are 80×80 cm (older) or 40×80 cm (newer). When considered as a subset of bed pillows, Euro pillows finish 26×26 in and older style travel pillows commonly finished 12×16 in. The main distinguishing feature is whether the pillow case is plain or with a valance around the edge. In the former case this is described as 'plain style' and in the latter as 'Oxford style'. "Oxford ... has

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5460-488: The abundance of acetylcholine in the brainstem) and perhaps from mechanisms used in waking muscle inhibition. The medulla oblongata , located between pons and spine, seems to have the capacity for organism-wide muscle inhibition. Some localized twitching and reflexes can still occur. Pupils contract. Lack of REM atonia causes REM behavior disorder , where those affected physically act out their dreams, or conversely "dream out their acts", under an alternative theory on

5565-404: The animal so that it appears dead . Tsoukalas argues that the neurophysiology and phenomenology of this reaction shows striking similarities to REM sleep; for example, both reactions exhibit brainstem control, cholinergic neurotransmission, paralysis, hippocampal theta rhythm, and thermoregulatory changes. According to "scanning hypothesis", the directional properties of REM sleep are related to

5670-435: The back of the neck and keeps the head from slipping into an uncomfortable and possibly harmful position during sleep. However, U-shaped pillows can sometimes force the head forward, creating neck stiffness. Doughnut pillows are firm pillows shaped like a torus , with a space in the middle to alleviate pressure on the tailbone area while sitting. These pillows are used primarily by individuals who have suffered an injury to

5775-434: The bed, they are primarily there for decoration, hence they fall under this category. These pillows may be custom made, as well as made by freelancers. Decorative pillows are also found on furnishings in more public parts of the home, such as sofas, chairs and window seats. Here, their common use may overlap both orthopedic and bed pillows. For example, unless a person has some particular medical condition, they will likely use

5880-403: The best evidence for REM's improvement of memory pertains to learning of procedures—new ways of moving the body (such as trampoline jumping), and new techniques of problem solving. REM deprivation seemed to impair declarative (i.e., factual) memory only in more complex cases, such as memories of longer stories. REM sleep apparently counteracts attempts to suppress certain thoughts. According to

5985-703: The body are sometimes called pillows. An example is eye pillows which are designed to comfort the eyes. Some mousemats feature wrist rests, that while not generally called pillows, are another example. A sex pillow is a specially-designed and typically firm pillow used to enhance sexual intercourse. An ordinary firm pillow, however, may be used in place of a special one. Some contain a high-density urethane core to balance firm support with softness. In addition to more common pillow shapes, there are wedge-shaped, ramp-shaped, prism-shaped, etc. pillows which lend themselves to various sexual positions, some of which might be difficult or uncomfortable without them. A very common use of

6090-440: The body, is accomplished through the inhibition of motor neurons . When the body shifts into REM sleep, motor neurons throughout the body undergo a process called hyperpolarization : their already-negative membrane potential decreases by another 2–10 millivolts , thereby raising the threshold which a stimulus must overcome to excite them. Muscle inhibition may result from unavailability of monoamine neurotransmitters (restraining

6195-406: The body. Sleep can be distributed throughout the day or clustered during one part of the rhythm: in nocturnal animals, during the day, and in diurnal animals, at night. The organism returns to homeostatic regulation almost immediately after REM sleep ends. During a night of sleep, humans usually experience about four or five periods of REM sleep; they are shorter (~15 min) at the beginning of

6300-502: The brain manifests differently than during wakefulness. Frontal and posterior areas are less coherent in most frequencies, a fact which has been cited in relation to the chaotic experience of dreaming. However, the posterior areas are more coherent with each other; as are the right and left hemispheres of the brain, especially during lucid dreams . Brain energy use in REM sleep, as measured by oxygen and glucose metabolism, equals or exceeds energy use in waking. The rate in non-REM sleep

6405-410: The brain exerts less control over breathing; electrical stimulation of respiration-linked brain areas does not influence the lungs, as it does during non-REM sleep and in waking. Erections of the penis ( nocturnal penile tumescence or NPT) normally accompany REM sleep in rats and humans. If a male has erectile dysfunction (ED) while awake, but has NPT episodes during REM, it would suggest that

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6510-515: The brain stem during REM. The withdrawal of orexin and GABA may cause the absence of the other excitatory neurotransmitters; researchers in recent years increasingly include GABA regulation in their models. Most of the eye movements in "rapid eye movement" sleep are in fact less rapid than those normally exhibited by waking humans. They are also shorter in duration and more likely to loop back to their starting point. About seven such loops take place over one minute of REM sleep. In slow-wave sleep,

6615-625: The case of memory foam can retain their form longer. Natural fillers have been used since antiquity. The most common are feathers , down , wool , latex , cotton (particularly in India ), and buckwheat . More exotic materials have also been used including straw, wood, or stone. Down is usually the softer filler and offer good insulation , but is more expensive due to its relative scarcity. Down has been known to be plucked from live geese , but there are already cruelty-free certifications for down products. In India, traditional pillows are made with kapok,

6720-491: The cerebral cortex"—a process they characterize as " unlearning ". As a result, those memories which are relevant (whose underlying neuronal substrate is strong enough to withstand such spontaneous, chaotic activation) are further strengthened, whilst weaker, transient, "noise" memory traces disintegrate. Memory consolidation during paradoxical sleep is specifically correlated with the periods of rapid eye movement, which do not occur continuously. One explanation for this correlation

6825-601: The change in electrical activity, measured by EEG, and loss of muscle tone, interspersed with bouts of twitching in phasic REM. The amount of REM sleep and cycling varies among animals; predators experience more REM sleep than prey. Larger animals also tend to stay in REM for longer, possibly because higher thermal inertia of their brains and bodies allows them to tolerate longer suspension of thermoregulation. The period (full cycle of REM and non-REM) lasts for about 90 minutes in humans, 22 minutes in cats, and 12 minutes in rats. In utero, mammals spend more than half (50–80%) of

6930-445: The chemical changes in the brain show continuous periodic oscillation. According to the activation-synthesis hypothesis proposed by Robert McCarley and Allan Hobson in 1975–1977, control over REM sleep involves pathways of "REM-on" and "REM-off" neurons in the brain stem. REM-on neurons are primarily cholinergic (i.e., involve acetylcholine); REM-off neurons activate serotonin and noradrenaline, which among other functions suppress

7035-500: The dreamer's recent experience taken directly from episodic memory . By one estimate, 80% of dreams occur during REM. Hobson and McCarley proposed that the PGO waves characteristic of "phasic" REM might supply the visual cortex and forebrain with electrical excitement which amplifies the hallucinatory aspects of dreaming. However, people woken up during sleep do not report significantly more bizarre dreams during phasic REMS, compared to tonic REMS. Another possible relationship between

7140-519: The dreams they were experiencing, and to estimate the duration of their dreams as longer. Lucid dreams are reported far more often in REM sleep. (In fact these could be considered a hybrid state combining essential elements of REM sleep and waking consciousness.) The mental events which occur during REM most commonly have dream hallmarks including narrative structure, convincingness (e.g., experiential resemblance to waking life), and incorporation of instinctual themes. Sometimes, they include elements of

7245-427: The effect of acetylcholine on neurons, has a similar influence. In waking humans, the same injections produce paradoxical sleep only if the monoamine neurotransmitters have already been depleted. Two other neurotransmitters , orexin and gamma-Aminobutyric acid (GABA), seem to promote wakefulness, diminish during deep sleep, and inhibit paradoxical sleep. Unlike the abrupt transitions in electrical patterns,

7350-404: The existence of similar PGO waves is thus inferred.) These waves occur in clusters about every 6 seconds for 1–2 minutes during the transition from deep to paradoxical sleep. They exhibit their highest amplitude upon moving into the visual cortex and are a cause of the "rapid eye movements" in paradoxical sleep. Other muscles may also contract under the influence of these waves. Research in

7455-459: The experience of dreaming during REMS. More recent PET research has indicated that the distribution of brain activity during REM sleep varies in correspondence with the type of activity seen in the prior period of wakefulness. The superior frontal gyrus , medial frontal areas , intraparietal sulcus , and superior parietal cortex , areas involved in sophisticated mental activity, show equal activity in REM sleep as in wakefulness. The amygdala

7560-479: The experimental animals decreases when REM sleep is totally attenuated during infection; this leads to the possibility that the quality and quantity of REM sleep is generally essential for normal body physiology. Further, the existence of a "REM rebound" effect suggests the possibility of a biological need for REM sleep. While the precise function of REM sleep is not well understood, several theories have been proposed. Sleep in general aids memory. REM sleep may favor

7665-497: The eyes can drift apart; however, the eyes of the paradoxical sleeper move in tandem. These eye movements follow the ponto-geniculo-occipital waves originating in the brain stem. The eye movements themselves may relate to the sense of vision experienced in the dream, but a direct relationship remains to be clearly established. Congenitally blind people, who do not typically have visual imagery in their dreams, still move their eyes in REM sleep. An alternative explanation suggests that

7770-403: The fluffy, glossy fruit-fibres of the trees Ceiba pentandra and Bombax ceiba . The normal lifespan of a typical western pillow is two to four years. Condition of the pillow can be determined by checking for lumps or folding it in order to see if it stays in that shape. Replacement is recommended for sanitary reasons. All types of pillow covers should be laundered periodically since they are

7875-499: The functional purpose of REM sleep is for procedural memory processing, and the rapid eye movement is only a side effect of the brain processing the eye-related procedural memory. Generally speaking, the body suspends homeostasis during paradoxical sleep. Heart rate , cardiac pressure, cardiac output , arterial pressure , and breathing rate quickly become irregular when the body moves into REM sleep. In general, respiratory reflexes such as response to hypoxia diminish. Overall,

7980-416: The hippocampus would be reinterpreted in relation to previous semantic representations or nodes." In the ultradian sleep cycle , an organism alternates between deep sleep (slow, large, synchronized brain waves) and paradoxical sleep (faster, desynchronized waves). Sleep happens in the context of the larger circadian rhythm , which influences sleepiness and physiological factors based on timekeepers within

8085-407: The home decor. The terms "sofa pillow" and "couch pillow" refer to the place these decorative pillows are likely found. The terms "toss pillow" and " throw pillow " may refer to the way they generally arrive in their places. Novelty pillows are shaped like humorous objects (a banana, tweety bird, a human leg, a chainsaw, a dill pickle, a former president) and are meant to brighten up and add humor to

8190-539: The intensity of REM sleep. These effects were the greatest during acute discontinuation compared to treatment and baseline days. However, the subjective intensity of dreaming increased and the proclivity to enter REM sleep was decreased during SSRI treatment compared to baseline and discontinuation days. After waking from REM sleep, the mind seems "hyperassociative"—more receptive to semantic priming effects. People awakened from REM have performed better on tasks like anagrams and creative problem solving. Sleep aids

8295-483: The late '90s and early 2000s, dakimakura began to intertwine with otaku culture, leading to the production of pillow covers featuring printed images of bishōjo and bishōnen posed lying down from various anime or bishōjo games . Many of these early otaku dakimakura covers were released through Cospa , a character goods and apparel store which as of 2018 continues to release official dakimakura covers. Although dakimakura are sometimes called "Dutch wife",

8400-528: The mess they can cause. Recycling of pillows, like most textile and bedding items, is expensive and has poor yield. As such, few are recycled and most end up in landfills. Their light weight means that they make up a low proportion of household waste by mass. Most of the few pillows collected for recycling are sent to India and Pakistan and used as low-cost bedding, or in South East Asia, co-mingled with other textiles to manufacture cheap bedding. A pillow

8505-504: The mid-2000s, dakimakura were available in one size; 160 cm × 50 cm (63 in × 20 in). Since the late 2000s, 150 cm × 50 cm (59 in × 20 in) dakimakura became available and increasingly popular due to shipping cost savings from being under the 2 kg (4 lb 7 oz) airmail weight limit. Due to the increase in popularity, new sizes have been created to adapt to all heights and ages, and although there are other sizes available,

8610-408: The modern human device dates back to the civilizations of Mesopotamia around 7,000 BC. During this time, only the wealthy used pillows. The number of pillows symbolized status so the more pillows one owned the more affluence they held. Pillows have long been produced around the world in order to help solve the reoccurring problem of neck, back, and shoulder pain while sleeping. Besides for comfort,

8715-554: The monoamine neurotransmitters which must be suppressed for REM sleep to occur. Administered at therapeutic doses, these drugs may stop REM sleep entirely for weeks or months. Withdrawal causes a REM rebound. Sleep deprivation stimulates hippocampal neurogenesis much as antidepressants do, but whether this effect is driven by REM sleep in particular is unknown. Although it manifests differently in different animals, REM sleep or something like it occurs in all land mammals —as well as in birds . The primary criteria used to identify REM are

8820-534: The most popular. The use of the ceramic pillow first appeared in the Sui dynasty between 581 and 618 while mass production appeared in the Tang dynasty between 618 and 907. The Chinese decorated their pillows by making them different shapes and by painting pictures of animals, humans, and plants on them. One common type of pottery used was Cizhou ware . Chinese ceramic pillows reached their peak in terms of production and use during

8925-400: The neck by providing a deep area for the head to rest and a supportive area to keep the neck in alignment with the spine while sleeping. These can also be known as cervical pillows. Cervical pillows help patients to maintain comfortable positioning after therapeutic, orthopedic and surgical measures. Travel pillows provide support for the neck in a sitting position. Their "U" shape fits around

9030-486: The need to re-examine the neurobiology of dreaming per se . Some researchers (Dement, Hobson, Jouvet, for example) tend to resist the idea of disconnecting dreaming from REM sleep. Previous research has shown that selective serotonin reuptake inhibitors (SSRIs) have an important effect on REM sleep neurobiology and dreaming. A study at Harvard Medical School in 2000 tested the effects of paroxetine and fluvoxamine on healthy young adult male and females for 31 days:

9135-405: The night and longer (~25 min) toward the end. Many animals and some people tend to wake, or experience a period of very light sleep, for a short time immediately after a bout of REM. The relative amount of REM sleep varies considerably with age. A newborn baby spends more than 80% of total sleep time in REM. REM sleep typically occupies 20–25% of total sleep in adult humans: about 90–120 minutes of

9240-508: The non-REM sleep improves the next-day recall of memorized pairs of words. Tucker et al. demonstrated that a daytime nap containing solely non-REM sleep enhances declarative memory —but not procedural memory . According to the sequential hypothesis , the two types of sleep work together to consolidate memory. Sleep researcher Jerome Siegel has observed that extreme REM deprivation does not significantly interfere with memory. One case study of an individual who had little or no REM sleep due to

9345-406: The organism which necessarily exceed the simple absence of a sleep phase. This method also stops working after about 3 days as the subjects (typically rats) lose their will to avoid the water. Another method involves computer monitoring of brain waves, complete with automatic mechanized shaking of the cage when the test animal drifts into REM sleep. Some researchers argue that the perpetuation of

9450-467: The original definition of this phrase is closer to the chikufujin , or "bamboo wife". The year 2015 saw some of the first talking body pillows with Ita-Supo and its mascot, Rina Makuraba. It was invented by former Kyushu Institute of Technology researcher, Koichi Uchimura. Dakimakura are available in two main sizes, 160 or 150 cm (63 or 59 in) in length with a 50 cm (20 in) width (100 cm (39 in) circumference). Prior to

9555-454: The part that is in contact with a person's body. Pillows accumulate dust and microbes among the fill, even when washable pillows are washed. Manufacturers recommend tumble-drying for fifteen minutes every week to freshen them up, and for the heat to kill dust mites. Charities in most countries will not accept used pillows due to hygiene regulations. While some animal shelters accept forms of bedding, most reject donation of used pillows due to

9660-405: The pillow was also used for keeping bugs and insects out of people's hair, mouth, nose, and ears while sleeping. Pillow use has been associated with the mummies and tombs of ancient Egypt during the 11th dynasty , dating to 2055–1985 B.C. Ancient Egyptian pillows were wooden or stone headrests. These pillows were mostly used by placing them under the heads of the deceased because the head of

9765-432: The pillowcase behind to keep it in..." Other methods of closure are ties or buttons/buttonholes. Body pillows are as long as a full adult body, providing support to the head and neck at the top and to the knees and legs lower down. This type of pillow can be especially useful in providing support for those who sleep on their sides and for pregnant women. Size is 40×140 cm. (See also: Dutch wife ) Neck pillows support

9870-460: The pons to prevent atonia have induced functional "REM behavior disorder" in animals. Rapid eye movement sleep (REM) has since its discovery been closely associated with dreaming . Waking up sleepers during a REM phase is a common experimental method for obtaining dream reports; 80% of neurotypical people can give some kind of dream report under these circumstances. Sleepers awakened from REM tend to give longer, more narrative descriptions of

9975-672: The population, it has repeatedly been shown to alleviate depression, albeit temporarily. More than half the individuals who experience this relief report it to be rendered ineffective after sleeping the following night. Thus, researchers have devised methods such as altering the sleep schedule for a span of days following a REM deprivation period and combining sleep-schedule alterations with pharmacotherapy to prolong this effect. Antidepressants (including selective serotonin reuptake inhibitors , tricyclics , and monoamine oxidase inhibitors ) and stimulants (such as amphetamine , methylphenidate and cocaine ) interfere with REM sleep by stimulating

10080-432: The preservation of certain types of memories : specifically, procedural memory , spatial memory , and emotional memory . In rats, REM sleep increases following intensive learning, especially several hours after, and sometimes for multiple nights. Experimental REM sleep deprivation has sometimes inhibited memory consolidation , especially regarding complex processes (e.g., how to escape from an elaborate maze). In humans,

10185-418: The process by which creativity forms associative elements into new combinations that are useful or meet some requirement. This occurs in REM sleep rather than in NREM sleep. Rather than being due to memory processes, this has been attributed to changes during REM sleep in cholinergic and noradrenergic neuromodulation . High levels of acetylcholine in the hippocampus suppress feedback from hippocampus to

10290-421: The proportion of REM sleep, as well as amount of total sleep. In other words, if at the end of a phase of deep sleep, the organism's thermal indicators fall outside of a certain range, it will not enter paradoxical sleep lest deregulation allow temperature to drift further from the desirable value. This mechanism can be 'fooled' by artificially warming the brain. REM atonia , an almost complete paralysis of

10395-735: The relationship between muscle impulses during REM and associated mental imagery (which would also apply to people without the condition, except that commands to their muscles are suppressed). This is different from conventional sleepwalking , which takes place during slow-wave sleep, not REM. Narcolepsy , by contrast, seems to involve excessive and unwanted REM atonia: cataplexy and excessive daytime sleepiness while awake, hypnagogic hallucinations before entering slow-wave sleep, or sleep paralysis while waking. Other psychiatric disorders including depression have been linked to disproportionate REM sleep. Patients with suspected sleep disorders are typically evaluated by polysomnogram . Lesions of

10500-427: The same overall intensity as in wakefulness. Electroencephalography during REM deep sleep reveals fast, low amplitude, desynchronized neural oscillation (brainwaves) that resemble the pattern seen during wakefulness, which differ from the slow δ (delta) waves pattern of NREM deep sleep. An important element of this contrast is the 3–10 Hz theta rhythm in the hippocampus and 40–60 Hz gamma waves in

10605-476: The tailbone area, or who suffer pain from hemorrhoids or another ailment of the colon . Lumbar pillows are designed to support the inward curve of the lower back , filling the space created between the lower back and the back of the chair when in a sitting position. These pillows are generally used to support the lower back while driving or sitting, such as in an office chair . Orthopedic pillows are similar to memory foam pillows. Decorative pillows serve

10710-457: The two phenomena could be that the higher threshold for sensory interruption during REM sleep allows the brain to travel further along unrealistic and peculiar trains of thought. Some dreaming can take place during non-REM sleep. "Light sleepers" can experience dreaming during stage 2 non-REM sleep, whereas "deep sleepers", upon awakening in the same stage, are more likely to report "thinking" but not "dreaming". Certain scientific efforts to assess

10815-425: The uniquely bizarre nature of dreams experienced while asleep were forced to conclude that waking thought could be just as bizarre, especially in conditions of sensory deprivation . Because of non-REM dreaming, some sleep researchers have strenuously contested the importance of connecting dreaming to the REM sleep phase. The prospect that well-known neurological aspects of REM do not themselves cause dreaming suggests

10920-424: The width of the textile, less seam allowance). A combination pillow is a pillow which is for those sleepers which are sleeping in a combination of positions and would like to use their pillow to hug or play. In many parts of the world, pillows have cultural significance, and references have extended to a wide variety of other uses, forms and activities. In some cultures, pillows have forms for hugging. An example

11025-800: The word pillow was before the 12th century. Though the exact origin is unknown, use of pillows evolved in animals well into prehistory, the earliest examples including reptiles and mammals resting their heads on themselves, and one another, to support the head and neck. Animals, including humans, evolved use of inanimate objects in their nests out of wood and stone as pillows. Since domestication , many animals have also learned to make use of human-made pillows and cushions, as well as to rest on members of their own and other species, for this purpose. Sometime between 5 and 23 million years ago tree-dwelling great apes began building sleeping platforms, including wooden pillows, to improve their sleep. According to studies on chimpanzees that sleep up to eight to nine hours

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