Why We Experience More Rem Sleep

REM sleep, or rapid-eye movement sleep, is one of four stages of sleep. Each sleep cycle lasts about 80 to 120 minutes, and we experience four to six sleep cycles per night. The first REM episode is short, lasting just a few minutes, but it lengthens with each subsequent cycle. By the end of the night, you may spend up to half an hour in REM sleep. This stage of sleep is associated with dreaming, memory consolidation, emotional processing, and brain development. While the purpose of REM sleep is not yet fully understood, it is known to be vital for overall health and well-being.

REM sleep is the fourth stage of sleep

REM sleep is the fourth and final stage of the sleep cycle. It is preceded by three stages of non-REM (NREM) sleep.

During REM sleep, the brain is highly active, with brain waves that resemble those during wakefulness. The eyes scurry rapidly behind closed eyelids, and breathing becomes irregular and faster. The heart rate also increases, and muscles become temporarily immobilised to prevent sleepers from acting out their dreams.

REM sleep is important for learning and memory consolidation, emotional processing, and brain development. It is also when most dreams occur.

Each sleep cycle, lasting between 90 and 120 minutes, includes a period of REM sleep. Typically, sleepers will go through four or five of these cycles per night, with each successive cycle devoting more time to REM sleep. The first REM cycle is the shortest, lasting around 10 minutes, while the final one may last up to an hour.

The amount of REM sleep needed changes throughout our lives. Newborns spend about half their sleep time in REM sleep, while adults only need about 20-25% of their total sleep to be REM sleep.

It is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity

During REM sleep, the body experiences a unique combination of physical and mental states. The first of these is muscle relaxation, where muscle tone is lost, and the body enters a state of temporary paralysis. This is believed to be a protective measure, preventing the sleeper from acting out their dreams and potentially injuring themselves. However, this hypothesis has been challenged by the discovery that dreams can also occur during non-REM sleep.

The "REM" in REM sleep refers to the rapid movement of the eyes, which move quickly behind closed eyelids. This is one of the most distinctive features of this sleep stage, giving it its name.

Breathing during REM sleep becomes irregular, and unlike the steady, slower breathing of non-REM sleep, it can vary depending on the activity in one's dreams. For example, if a person is running in their dream, their breathing and heart rate may increase as if they were awake.

The heart rate during REM sleep is typically elevated and can vary significantly. If a dream is particularly scary or involves physical activity, the heart rate rises accordingly. This is in contrast to non-REM sleep, where the heart rate slows down.

REM sleep is also characterised by increased brain activity. Brain waves during this stage are similar to those observed during wakefulness, with brain activity highly active and brain waves more variable. This is in contrast to non-REM sleep, where brain waves slow down. The brain activity during REM sleep is associated with dreaming, memory consolidation, emotional processing, and brain development.

Most adults need about two hours of REM sleep each night

Sleep is a period during which the brain is engaged in a number of activities necessary for life and closely linked to quality of life. A good night's sleep is essential for maintaining good health and well-being.

Sleep occurs in cycles, with each cycle lasting about 80 to 120 minutes. The first part of the cycle is non-REM sleep, which is composed of four stages: the first stage comes between being awake and falling asleep; the second is light sleep, when heart rate and breathing regulate and body temperature drops; and the third and fourth stages are deep sleep. After these non-REM stages, the brain enters REM sleep.

REM sleep is characterised by relaxed muscles, quick eye movement, irregular breathing, elevated heart rate, and increased brain activity. Most adults need about two hours of REM sleep each night. REM sleep plays a role in memory consolidation, emotional processing, brain development, and dreaming. It is also associated with learning new information and maintaining important neural pathways.

The amount of REM sleep a person gets can vary from night to night, depending on what their body needs. If you don't get enough REM sleep one night, your body will naturally increase it the next night—you'll enter this stage earlier and stay in it for longer. This is known as REM rebound.

Getting enough total sleep helps to maximise REM sleep, as most REM sleep occurs at the end of the night. Sticking to a sleep schedule and limiting alcohol and caffeine can help improve sleep quality. Regular physical activity can also increase the amount of deep, restorative sleep, which boosts mood and energy.

It is important for memory consolidation, emotional processing, brain development, and dreaming

REM sleep is important for several reasons, including memory consolidation, emotional processing, brain development, and dreaming.

Memory Consolidation

Memory consolidation is the process of committing new learnings and motor skills from the day to memory. During REM sleep, the brain processes this information, deciding what to keep, what to discard, and what to maintain. While some memory consolidation also takes place during deep sleep, a non-REM stage, REM sleep is thought to be particularly important for procedural memory, which involves performance on perceptual and perceptuo-motor skills.

Emotional Processing

REM sleep is associated with emotional memories, and people who get more REM sleep are better at assessing others' emotional intentions and recalling emotional stories. This may be due to the absence of the stress hormone noradrenaline during REM sleep, allowing the brain to process memories without interference from stress. REM sleep also appears to help regulate emotional responses, with sleepers exhibiting a smaller emotional response in late positive potential (LPP) – a voltage measured at the back of the brain that spikes when processing negative emotions.

Brain Development

REM sleep is thought to promote brain development, as newborns spend most of their sleep time in this stage. This hypothesis is supported by the fact that animals born with less developed brains, such as humans and puppies, spend more time in REM sleep during infancy than those born with more developed brains, like horses and birds. Recent findings have also shown that REM sleep is important for pruning and maintaining new synapses in the developing brain, a process critical for normal neuronal circuit development and behavioral improvement after learning.

Dreaming

A majority of dreams occur during REM sleep, and these dreams tend to be more vivid than those that occur during non-REM sleep. While the function of dreams is not fully understood, they are thought to be involved in emotional processing, as they often involve recent emotional experiences or content.

Lack of REM sleep is associated with neurological issues and an increased risk of Alzheimer's disease and Parkinsonism

Sleep is essential for our health, and one particular stage of sleep, REM sleep, is vital for brain health and function. REM sleep is the fourth and final stage of the sleep cycle, and it is when most of our dreams occur. During REM sleep, our heart rate, blood pressure, brain activity, and breathing increase, and our eyes move rapidly behind closed eyelids.

REM sleep is important for several reasons. Firstly, it aids in memory consolidation and emotional processing, as our brain processes emotions and memories during this stage. Secondly, it plays a crucial role in brain development, especially in infants and newborns, who spend a significant portion of their sleep time in REM sleep.

However, a lack of REM sleep has been linked to various neurological issues and an increased risk of certain neurodegenerative diseases. Research has shown that insufficient REM sleep may be associated with an increased risk of dementia, including Alzheimer's disease. A study published in the journal Neurology found that individuals who went on to develop dementia spent less of their sleep time in REM sleep compared to those who didn't.

Additionally, REM sleep behaviour disorder (RBD) has been identified as an early sign of Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. People with RBD act out their dreams due to a loss of muscle paralysis during REM sleep. Autopsies of individuals with RBD have revealed the presence of alpha-synuclein aggregates, protein clumps in brain regions regulating REM sleep.

The relationship between REM sleep and neurological issues is a complex area of ongoing research. While the exact mechanisms are not yet fully understood, it is clear that maintaining adequate REM sleep is crucial for brain health and may help reduce the risk of developing neurodegenerative diseases.

Frequently asked questions