Increasing

According to Tsoukalas (2012) 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 the animal: the animal appears dead (cf. "playing possum"). The neurophysiology and phenomenology of this reaction shows striking similarities to REM sleep, a fact which betrays a deep evolutionary kinship. For example, both reactions exhibit brainstem control, paralysis, sympathetic activation, and thermoregulatory changes. This theory integrates many earlier findings into a unified, and evolutionary well informed, framework.[47]
Dreams as excitations of long-term memory

Eugen Tarnow suggests that dreams are ever-present excitations of long-term memory, even during waking life. The strangeness of dreams is due to the format of long-term memory, reminiscent of Penfield & Rasmussen's findings that electrical excitations of the cortex give rise to experiences similar to dreams. During waking life an executive function interprets long-term memory consistent with reality checking. Tarnow's theory is a reworking of Freud's theory of dreams in which Freud's unconscious is replaced with the long-term memory system and Freud's "Dream Work" describes the structure of long-term memory.[51]
Dreams for strengthening of semantic memories
Location of hippocampus

A 2001 study showed evidence that illogical locations, characters, and dream flow may help the brain strengthen the linking and consolidation of semantic memories.[52] These conditions may occur because, during REM sleep, the flow of information between the hippocampus and neocortex is reduced.[53]

Increasing levels of the stress hormone cortisol late in sleep (often during REM sleep) cause this decreased communication. One stage of memory consolidation is the linking of distant but related memories. Payne and Nadal hypothesize these memories are then consolidated into a smooth narrative, similar to a process that happens when memories are created under stress.[54]
Dreams for removing excess sensory information

Robert (1886),[55] a physician from Hamburg, was the first who suggested that dreams are a need and that they have the function to erase (a) sensory impressions that were not fully worked up, and (b) ideas that were not fully developed during the day. By the dream work, incomplete material is either removed (suppressed) or deepened and included into memory. Robert's ideas were cited repeatedly by Freud in his Die Traumdeutung. Hughlings Jackson (1911) viewed that sleep serves to sweep away unnecessary memories and connections from the day.

This was revised in 1983 by Crick and Mitchison's "reverse learning" theory, which states that dreams are like the cleaning-up operations of computers when they are off-line, removing (suppressing) parasitic nodes and other "junk" from the mind during sleep.[56][57] However, the opposite view that dreaming has an information handling, memory-consolidating function (Hennevin and Leconte, 1971) is also common. Dreams are a result of the spontaneous firings of neural patterns while the brain is undergoing memory consolidation while sleeping.
Psychological theories of dreams
Dreams for testing and selecting mental schemas

Combining

When REM sleep episodes were timed for their duration and subjects woken to make reports before major editing or forgetting could take place, it was determined that subjects accurately matched the length of time they judged the dream narrative to be ongoing to the length of REM sleep that preceded the awakening. There is no "time dilation" effect; a five-minute dream takes roughly five minutes of real time to play out.[41] This close correlation of REM sleep and dream experience was the basis of the first series of reports describing the nature of dreaming: that it is a regular nightly, rather than occasional, phenomenon, and a high-frequency activity within each sleep period occurring at predictable intervals of approximately every 60–90 minutes in all humans throughout the life span.

REM sleep episodes and the dreams that accompany them lengthen progressively across the night, with the first episode being shortest, of approximately 10–12 minutes duration, and the second and third episodes increasing to 15–20 minutes. Dreams at the end of the night may last as long as 15 minutes, although these may be experienced as several distinct stories due to momentary arousals interrupting sleep as the night ends. Dream reports can be reported from normal subjects on 50% of the occasion when an awakening is made prior to the end of the first REM period. This rate of retrieval is increased to about 99% when awakenings are made from the last REM period of the night. This increase in the ability to recall appears related to intensification across the night in the vividness of dream imagery, colors, and emotions.[42]
Dreams in animals

REM sleep and the ability to dream seem to be embedded in the biology of many animals that live on Earth. All mammals experience REM. The range of REM can be seen across species: dolphins experience minimum REM, while humans remain in the middle and the opossum and the armadillo are among the most prolific dreamers.[43]

Studies have observed dreaming in mammals such as monkeys, dogs, cats, rats, elephants and shrews. There have also been signs of dreaming in birds and reptiles.[44] Sleeping and dreaming are intertwined. Scientific research results regarding the function of dreaming in animals remain disputable; however, the function of sleeping in living organisms is increasingly clear. For example, recent sleep deprivation experiments conducted on rats and other animals have resulted in the deterioration of physiological functioning and actual tissue damage of the animals.[45]

Some scientists argue that humans dream for the same reason other amniotes do. From a Darwinian perspective dreams would have to fulfill some kind of biological requirement, provide some benefit for natural selection to take place, or at least of have no negative impact on fitness. In 2000 Antti Revonsuo, a professor at the University of Turku in Finland, claimed that centuries ago dreams would prepare humans for recognizing and avoiding danger by presenting a simulation of threatening events. The theory has therefore been called the threat-simulation theory.[46] According to Tsoukalas (2012) dreaming is related to the reactive patterns elicited by predatorial encounters, a fact that is still evident in the control mechanisms of REM sleep (see below).[47]
Neurological theories of dreams
Activation synthesis theory
Main article: Activation-synthesis hypothesis

In 1976 J. Allan Hobson and Robert McCarley proposed a new theory that changed dream research, challenging the previously held Freudian view of dreams as unconscious wishes to be interpreted. They assume that the same structures that induce REM sleep also generate sensory information. Hobson's 1976 research suggested that the signals interpreted as dreams originated in the brain stem during REM sleep. However, research by Mark Solms suggests that dreams are generated in the forebrain, and that REM sleep and dreaming are not directly related.[48]

While working in the neurosurgery department at hospitals in Johannesburg and London, Solms had access to patients with various brain injuries. He began to question patients about their dreams and confirmed that patients with damage to the parietal lobe stopped dreaming; this finding was in line with Hobson's 1977 theory. However, Solms did not encounter cases of loss of dreaming with patients having brain stem damage. This observation forced him to question Hobson's prevailing theory, which marked the brain stem as the source of the signals interpreted as dreams.
Continual-activation theory

Combining Hobson's activation synthesis hypothesis with Solms' findings, the continual-activation theory of dreaming presented by Jie Zhang proposes that dreaming is a result of brain activation and synthesis; at the same time, dreaming and REM sleep are controlled by different brain mechanisms. Zhang hypothesizes that the function of sleep is to process, encode and transfer the data from the short-term memory to the long-term memory, though there is not much evidence backing up this so-called "consolidation." NREM sleep processes the conscious-related memory (declarative memory), and REM sleep processes the unconscious related memory (procedural memory).

Zhang assumes that during REM sleep the unconscious part of a brain is busy processing the procedural memory; meanwhile, the level of activation in the conscious part of the brain descends to a very low level as the inputs from the sensory are basically disconnected. This triggers the "continual-activation" mechanism to generate a data stream from the memory stores to flow through the conscious part of the brain. Zhang suggests that this pulse-like brain activation is the inducer of each dream. He proposes that, with the involvement of the brain associative thinking system, dreaming is, thereafter, self-maintained with the dreamer's own thinking until the next pulse of memory insertion. This explains why dreams have both characteristics of continuity (within a dream) and sudden changes (between two dreams).[49][50]
Defensive immobilization: the precursor of dreams

The neurobiology

Carl Jung rejected many of Freud's theories. Jung expanded on Freud's idea that dream content relates to the dreamer's unconscious desires. He described dreams as messages to the dreamer and argued that dreamers should pay attention for their own good. He came to believe that dreams present the dreamer with revelations that can uncover and help to resolve emotional or religious problems and fears.[32]

Jung wrote that recurring dreams show up repeatedly to demand attention, suggesting that the dreamer is neglecting an issue related to the dream. He believed that many of the symbols or images from these dreams return with each dream. Jung believed that memories formed throughout the day also play a role in dreaming. These memories leave impressions for the unconscious to deal with when the ego is at rest. The unconscious mind re-enacts these glimpses of the past in the form of a dream. Jung called this a day residue.[33] Jung also argued that dreaming is not a purely individual concern, that all dreams are part of "one great web of psychological factors."

Fritz Perls presented his theory of dreams as part of the holistic nature of Gestalt therapy. Dreams are seen as projections of parts of the self that have been ignored, rejected, or suppressed.[34] Jung argued that one could consider every person in the dream to represent an aspect of the dreamer, which he called the subjective approach to dreams. Perls expanded this point of view to say that even inanimate objects in the dream may represent aspects of the dreamer. The dreamer may, therefore, be asked to imagine being an object in the dream and to describe it, in order to bring into awareness the characteristics of the object that correspond with the dreamer's personality.
The neurobiology of dreaming
Main article: Rapid eye movement sleep
EEG showing brainwaves during REM sleep

Accumulated observation has shown that dreams are strongly associated with rapid eye movement sleep, during which an electroencephalogram (EEG) shows brain activity that, among sleep states, is most like wakefulness. Participant-remembered dreams during NREM sleep are normally more mundane in comparison.[35] During a typical lifespan, a person spends a total of about six years dreaming[36] (which is about two hours each night).[37] Most dreams only last 5 to 20 minutes.[36] It is unknown where in the brain dreams originate, if there is a single origin for dreams or if multiple portions of the brain are involved, or what the purpose of dreaming is for the body or mind.

During REM sleep, the release of the neurotransmitters norepinephrine, serotonin and histamine is completely suppressed.[38][39][40]

Furinno FNAJ-11073 Boyate Magic Cube Five Grid Storage Rack, Walnut

Product Description

Furinno Boyate Home Living Space Saving Decorative Display shelf is (1) Unique Structure: designed with simple yet stylish appearance. We focus on products that fit in your space and fit on your budget. (2) Easy Assembly: with reference to the assembly instruction, this unit can be assembled in as short as 60 minutes. Designed to meet the demand of low cost but durable and efficient furniture. (3) Made from E1 grade engineered particle board with high durability and without harsh chemicals. Thus there is no foul smell. Closer to healthy living and nature. A simple attitude towards lifestyle is reflected directly on the design of Furinno Furniture, creating a trend of simply nature. Products are produced 100-percent in China . Care instructions: wipe clean with clean damp cloth. Avoid using harsh chemicals. Pictures are for illustration purpose. All decor items are not included in this offer.

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InterMetro Over Bed Storage Shelf

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Quantum Storage Systems WR63-2124C Starter Kit for 63" High 4-Tier Wire Shelving Unit, Chrome Finish, 21" Width x 24" Length x 63" Height

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Winsome Trading 7pc Storage 4-Tier Shelf with 6 Small Baskets

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Categories: storage shelving