Dream States: Rem Vs. Nrem Sleep

Dreams occur during both REM and non-REM sleep. However, dreams that occur during REM sleep tend to be longer, more vivid, bizarre, emotional, and story-like. In contrast, non-REM dreams are more thought-like and conceptual.

Dreams occur during both REM and non-REM sleep

The Sleep Cycle

During sleep, the body cycles through different stages, including non-REM and REM sleep. Non-REM sleep is further divided into three substages: N1, N2, and N3. Each cycle lasts between 90 and 120 minutes, and as the night progresses, the amount of time spent in REM sleep increases.

Non-REM Sleep

The first stage of sleep is N1, characterised by slow heartbeat and breathing, and slow, rolling eye movements. It is easy to wake someone during this stage, and they may not even realise they were asleep.

The second stage, N2, is a deeper sleep where body temperature drops and breathing and heart rate slow further. People spend most of their time asleep in this stage and can be woken up, but it is not as easy as in N1.

The third stage, N3, is deep sleep, during which the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system. It is difficult to wake someone during this stage, and if awakened, they would feel disoriented for a few minutes.

REM Sleep

REM sleep is characterised by rapid eye movement, increased brain activity, irregular breathing, and elevated heart rate. The eyes move rapidly, and the body experiences temporary paralysis. Dreams that occur during REM sleep tend to be more vivid and elaborate, following a narrative structure.

Differences Between REM and Non-REM Sleep

In addition to the differences in the nature of dreams, there are several other distinctions between REM and non-REM sleep. During non-REM sleep, the eyes do not move, brain waves are slower, and there is partial muscle tone. In contrast, during REM sleep, brain wave activity is similar to that of wakefulness, there is a complete loss of muscle tone, breathing becomes irregular, and the heart rate rises. It is also easier to wake someone during REM sleep than during non-REM sleep.

The Importance of REM Sleep

REM sleep plays a crucial role in several important functions, including dreaming, memory consolidation, emotional processing, and brain development. While dreams can occur during non-REM sleep, they are typically more vivid and memorable during REM sleep. REM sleep also aids in emotional processing by activating the amygdala, the part of the brain responsible for processing emotions. Additionally, REM sleep is involved in memory consolidation, where the brain processes and commits new learnings and motor skills to memory.

Furthermore, REM sleep is crucial for brain development, especially in infants and children whose brains are still developing. Newborn babies spend up to eight hours in REM sleep each day, and this decreases to an average of two hours per night in adulthood.

The Impact of REM Sleep Deprivation

Deprivation of REM sleep can interfere with memory formation and disrupt the brain's ability to generate new cells. However, this could also be due to overall sleep disruption, as REM sleep deprivation often occurs alongside a lack of sleep in general. Signs of REM sleep deprivation include difficulty concentrating during the day, excessive daytime sleepiness, and forgetfulness or poor memory.

Dreams during REM sleep are more vivid, bizarre, and emotional

REM sleep is characterised by rapid eye movement, increased brain activity, irregular breathing, and elevated heart rate. It is during this stage that most dreams occur. The dreams that occur during REM sleep tend to be more vivid and bizarre due to the heightened brain activity. The content of these dreams can be illogical or incoherent, and often involves fantastical elements.

While dreams can occur during any stage of sleep, it is the dreams during REM sleep that are typically more memorable and emotionally impactful. This is because, during REM sleep, the amygdala, the part of the brain responsible for processing emotions, is activated. This emotional processing during REM sleep leads to dreams that are more emotionally charged and memorable.

Furthermore, the structure of dream reports collected during REM sleep differs from those collected during non-REM sleep. Dream reports from REM sleep have been found to be longer and have larger connectedness compared to non-REM dream reports. This indicates that dreams during REM sleep tend to have a more complex narrative structure, with words and ideas recurring over a longer range, resulting in more elaborate and interconnected dream sequences.

In summary, dreams during REM sleep are more vivid, bizarre, and emotional due to increased brain activity, emotional processing, and the complex narrative structure of dreams during this sleep stage.

Dreams during non-REM sleep are more abstract and conceptual

Dreaming occurs during both REM and non-REM sleep, but the nature of dreams differs between the two. Dreams during non-REM sleep tend to be more abstract and conceptual, while dreams during REM sleep are more vivid, bizarre, and emotional.

A 2020 study published in the *PLOS One* journal analysed dream reports from 20 participants who were woken up during REM sleep and non-REM sleep. The researchers found that dreams during the non-REM phase were more abstract and less elaborate, while dreams during the REM phase were more vivid and followed a narrative structure.

Another study published in the same journal in 2020 used graph analysis to compare the structural differences between REM and non-REM dream reports. The results showed that REM dream reports had larger structural connectedness than non-REM dream reports. This suggests that dreams during REM sleep are more interconnected and coherent, while dreams during non-REM sleep may be more fragmented and isolated.

During REM sleep, the eyes move rapidly, and the brain is active. This stage of sleep is associated with intense dreams and is important for learning and memory. On the other hand, non-REM sleep is characterised by slower brain activity and decreased heart rate and breathing. The deeper stages of non-REM sleep are crucial for tissue repair, muscle building, and strengthening the immune system.

REM sleep is also known as active sleep, paradoxical sleep, and dream sleep

Active Sleep

During REM sleep, the eyes move rapidly in different directions, and the brain is active. Brain activity during REM sleep is similar to its activity when a person is awake. The muscles go limp during REM sleep, so that people do not act out their dreams.

Paradoxical Sleep

REM sleep is also known as paradoxical sleep because it is characterised by high levels of brain metabolic demand and attenuation of homeostatic regulation. This makes it difficult to understand how animals benefit from this state. For example, the suppression of REM sleep through drug use does not have any striking effect on behaviour.

Dream Sleep

Dreams typically occur during REM sleep. This was first discovered by Aserinsky and Kleitman, who found that dreaming was associated with a state of low voltage EEG and eye movements during sleep.

Non-REM sleep is also known as light sleep

Non-REM sleep is divided into three substages: N1, N2, and N3. N1 is the lightest stage of sleep, followed by N2, which is deeper, and then N3, which is the deepest stage of sleep.

During N1, it is easy to wake the sleeper, and they may not even realise that they had dozed off. This phase may last for 5 to 10 minutes.

In N2, the person is in light sleep but it is deeper than N1. Their heart rate and breathing slow down further, and their body temperature drops as they get ready for deep sleep. This stage can last from 10 to 25 minutes.

N3 is the deep sleep stage, also known as delta sleep or slow-wave sleep. It is harder to wake someone during this stage, and if they are woken up, they will likely experience sleep inertia, feeling disoriented and mentally foggy for a few minutes. This is the stage when the body repairs itself, boosts the immune system, and restores bones, muscles, and tissues. N3 sleep makes up about 25% of total sleep time in adults, but the percentage is higher in babies and children. As people get older, the amount of N3 sleep they get decreases.

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