Understanding N Sleep: More Important Than Rem?

Sleep is a complex and mysterious process that is essential for the body and brain to rest and recover. While asleep, the body cycles between non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep is characterised by slower brain waves, decreased heart rate and breathing, and tissue repair, while REM sleep is associated with dreaming, memory consolidation, emotional processing, and brain development. Both types of sleep are important, but the question remains: which is more beneficial for overall health and well-being?

REM sleep is important for brain development and memory consolidation

Brain Development

Researchers hypothesize that REM sleep promotes brain development, especially in newborns, who spend most of their sleep time in this stage. This 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 mature brains, like horses and birds.

REM sleep has been shown to selectively prune newly formed dendritic spines in the developing brain and strengthen new synapses, which is critical for normal neuronal circuit development and behavioral improvement after learning.

Memory Consolidation

REM sleep is also important for memory consolidation, with the brain processing new learnings and motor skills from the day, deciding which ones to keep and which to delete. The activation of the amygdala, the part of the brain that processes emotions, during REM sleep may also play a role in emotional learning and memory consolidation.

While the link between REM sleep and memory consolidation has been contested, with some studies finding no correlation, others have shown that sleep disruption before learning does affect performance in learning tasks.

Non-REM sleep is when the body repairs and regrows tissues

Non-REM sleep is when the body undergoes several physiological changes that contribute to muscle recovery. During this stage, the body repairs and regrows tissues, builds bone and muscle, and strengthens the immune system.

During a training session, you challenge your muscles to handle higher levels of resistance or weight than they normally do, which breaks down the muscle tissue, causing microscopic tears. This "damage" activates cells from outside the muscle fibres, which rush to the area of the tears, replicate, mature into grown cells, and fuse to your muscle fibres. This process forms new muscle protein strands and, over time, increases muscle strength and mass.

Sleep is essential for this process of muscle recovery. When we sleep, our body undergoes several physiological changes that aid in the repair and recovery of damaged tissues. These changes are necessary for muscle recovery, especially after a workout or an injury.

During Non-REM sleep, the body releases human growth hormone (HGH), which plays a crucial role in muscle repair and growth. HGH stimulates protein synthesis, the process by which damaged muscle fibres are repaired and new muscle tissue is built. Research has shown that the more deep sleep you get, the more HGH is released. Conversely, when you get less sleep, there is less growth hormone secretion.

In addition to muscle repair and growth, Non-REM sleep is also important for replenishing muscle glycogen, a critical energy source that gets depleted when we work out. Sleep is also when the body restores glycogen levels, ensuring that muscles have enough fuel for optimal performance.

Furthermore, Non-REM sleep helps regulate hormone levels that are important for muscle recovery, such as testosterone, which promotes muscle growth and repair. Lack of sleep can disrupt testosterone production, which may negatively impact muscle recovery.

Finally, Non-REM sleep plays a role in reducing inflammation in the body. Intense exercise can cause muscle damage and inflammation. During Non-REM sleep, the body releases anti-inflammatory cytokines that help reduce inflammation and promote healing.

Sleep is important for maintaining physical and mental health

Sleep is essential for maintaining physical and mental health. During sleep, the body and brain undergo a series of changes that promote recovery and prepare the individual for the upcoming day. Sleep is typically divided into two types: rapid-eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. Each serves distinct purposes and contributes to overall health in unique ways.

NREM sleep is characterised by slower brain waves, decreased heart rate and body temperature, and relaxed muscles. It is during this stage that the body physically repairs itself. This includes boosting the immune system and restoring bones, muscles, and tissues. NREM sleep is also when the body conserves energy and stores resources for the next day.

On the other hand, REM sleep is associated with more rapid eye movements, increased brain activity, irregular breathing, and elevated heart rate. This stage is crucial for brain health and function. It stimulates areas of the brain that aid in learning, memory, and emotional processing. Dreams, which are believed to help process emotions, typically occur during REM sleep.

The amount of sleep needed varies across the lifespan. Newborns require the most sleep, ranging from 14 to 17 hours per day, while adults are recommended to get 7 to 9 hours of sleep per night. However, it's important to note that the quality of sleep is also crucial. Sleep deprivation can lead to cognitive impairments, mood disturbances, a weakened immune system, and an increased risk of various health conditions, including diabetes, depression, obesity, and cardiovascular disease.

To maintain physical and mental health, it is essential to prioritise sleep and practice good sleep hygiene. This includes sticking to a consistent sleep schedule, creating a relaxing bedtime routine, avoiding bright lights and electronics before bed, and refraining from consuming caffeine and alcohol close to bedtime.

Dreaming occurs in both REM and non-REM sleep

During REM sleep, your brain activity is similar to its activity when you are awake. This is when most dreams occur, and they can be intense. Your eyes move rapidly behind closed eyelids, and your muscles go limp so that you don't act out your dreams. REM sleep stimulates the areas of your brain that help with learning and memory, and it is important for mood regulation and brain development.

During non-REM sleep, your brain is not as active, and your heart rate, breathing, and body temperature decrease. This is when your body repairs and regrows tissues, builds bone and muscle, and strengthens your immune system. While dreams during non-REM sleep are less common, they tend to be more abstract and harder to remember.

Each sleep cycle, which lasts between 90 and 120 minutes, includes three stages of non-REM sleep followed by a stage of REM sleep. You typically go through four or five cycles per night. The first REM episode is usually short, lasting only a few minutes, but each subsequent episode lengthens, with the final one lasting up to an hour.

While you might not remember your dreams from non-REM sleep, a 2020 study found that dream recall was more prevalent after REM sleep. Participants reported more abstract dreams during non-REM sleep and more elaborate, narrative dreams during REM sleep.

Sleep cycles last between 90 and 120 minutes

Sleep cycles, which include three stages of non-rapid eye movement (NREM) sleep and one rapid eye movement (REM) stage, typically last between 90 and 120 minutes. The duration of each sleep stage can vary from person to person and from night to night, depending on factors such as age, recent sleep patterns, and alcohol consumption.

The first sleep cycle is often the shortest, ranging from 70 to 100 minutes, while later cycles tend to fall between 90 and 120 minutes. As the night progresses, the composition of each cycle changes, with more time spent in REM sleep during the second half of the night.

During a typical night, a person goes through four to six sleep cycles. If you get a full eight hours of sleep, you will usually go through four or five cycles. The first REM episode is usually brief, lasting only a few minutes, but each subsequent cycle becomes longer. By the end of the night, you may spend up to 30 minutes in REM sleep.

Understanding the sleep cycle is crucial in explaining how sleep disorders, such as insomnia and obstructive sleep apnea, can impact an individual's sleep and overall health.

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