Rem Vs Nrem: Understanding Sleep Stages Better

Sleep is divided into two types: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep is further divided into four stages, each with unique characteristics, including variations in brain wave patterns, eye movements, and muscle tone. During the first stage of NREM sleep, the brain slows down, and the body relaxes. In the second stage, the body temperature drops, and breathing and heart rate become more regular. The third and fourth stages are deep sleep, during which the body repairs and restores itself. REM sleep, on the other hand, is characterised by rapid eye movement, increased brain activity, and dreaming.

NREM sleep is divided into four stages, each with unique characteristics

The second stage is a lighter sleep, where individuals become less aware of their surroundings. The body temperature drops, eye movements stop, and breathing and heart rate become more regular. The brain also begins to produce bursts of rapid, rhythmic brain wave activity, known as sleep spindles, which are thought to be a feature of memory consolidation. This stage lasts for about 20 minutes per cycle, and people spend about half of their total sleep time in this stage.

The third and fourth stages are collectively referred to as slow-wave sleep (SWS). This is a deep sleep stage where the sleeper is harder to wake. During this stage, the muscles are completely relaxed, blood pressure drops, and breathing slows. The body starts its physical repairs in this stage, and the brain consolidates declarative memories.

The four stages of NREM sleep are each associated with distinct brain activity and physiology, including variations in brain wave patterns, eye movements, and muscle tone.

NREM sleep is restorative and accounts for around 75-80% of total sleep time

NREM sleep is the most restorative sleep and accounts for around 75-80% of our total sleep time. During NREM sleep, our brain waves, heart rate, and breathing slow down. Our body uses this time to clean up the brain, grow and repair our bones, muscles, tissues, and organs, and balance our hormones.

NREM sleep is divided into four stages, each with unique characteristics. The first stage is the lightest sleep, where our brainwaves slow down, our heartbeat slows, and our muscles start to relax. This is the phase where people sometimes experience muscle jerks or the feeling of falling. The second stage is a deeper sleep, where people become less aware of their surroundings, their body temperature drops, their eye movements stop, and their breathing and heart rate become more regular. The brain also begins to produce bursts of rapid, rhythmic brain wave activity, which are known as sleep spindles, thought to be a feature of memory consolidation. The third and fourth stages are deep sleep, where our brainwaves, breathing, and heartbeat slow right down, and the body is fully relaxed. This is the most difficult stage to wake someone from, and if they do wake up, they will probably experience sleep inertia, a state of confusion or "mental fog" that lasts about 30 minutes. During this deep sleep stage, the body starts its physical repairs, and the brain consolidates declarative memories.

Throughout the night, we cycle between NREM and REM sleep. A typical night's sleep consists of 4 to 5 sleep cycles, with the progression of sleep stages in the following order: N1, N2, N3, N2, and REM. The first cycle normally takes about 90 to 120 minutes before another begins.

REM sleep is when the brain is active and we are more inclined to dream

REM sleep is one of the two types of sleep, the other being non-REM (NREM) sleep. During REM sleep, the brain is highly active and uses more oxygen than when we are awake. The brain replays the events of the day, removing distracting background noise and saving important information in our long-term memory. The brain also reviews long-term memory, rearranging information and removing unnecessary data.

REM sleep is named after the rapid eye movement that occurs during this phase. The body is still relaxed, but the eyes move rapidly, the heart rate increases, breathing becomes more erratic, and body temperature increases. Dreaming mostly occurs during REM sleep, and the brain activity during this stage is similar to when we are awake.

The amount of time spent in REM sleep changes throughout our lives. For example, REM sleep is half the total sleeping time of infants, but it drops to about 25% by the age of 10 years.

Sleep cycles and stages were discovered using electroencephalographic (EEG) recordings

NREM sleep is further divided into four stages, each with unique characteristics, including variations in brain wave patterns, eye movements, and muscle tone. Stage 1 is the lightest stage of sleep, where the brain slows down, and the heartbeat, eye movements, and breathing slow with it. Stage 2 is a deeper sleep where the body temperature drops, eye movements stop, and breathing and heart rate become more regular. Stages 3 and 4 are deep sleep stages, where the brain produces slow brain waves, the body is fully relaxed, and physical repairs occur.

REM sleep is characterised by rapid eye movement and is when most dreams occur. During this stage, the brain's activity is similar to when we are awake, but the body is temporarily paralysed. This stage is important for memory consolidation and the processing of emotions and emotional memories.

Throughout the night, the body cycles between NREM and REM sleep, with each cycle lasting around 90 to 120 minutes. The progression of sleep stages follows the sequence: NREM stage 1, NREM stage 2, NREM stage 3, repeat of NREM stage 2, and finally, REM sleep. The time spent in each stage changes throughout the night as the cycle repeats four to five times.

Sleepwalking and bedwetting occur during the deep sleep phase of the sleep cycle

Sleep is divided into two main types: non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep is further divided into four stages, each with unique characteristics, including variations in brain wave patterns, eye movements, and muscle tone. The first three stages are considered NREM sleep, while the fourth is REM sleep.

The third stage of NREM sleep is the deepest stage of sleep, during which the body repairs injuries and reinforces the immune system. It is also during this stage that sleepwalking and bedwetting occur. Sleepwalking, or somnambulism, typically occurs during the early part of the night's sleep and is more common in children and young adults than in older adults. Bedwetting, or sleep enuresis, is considered a parasomnia when it occurs in children aged five and older at least twice a week for at least three months.

During the REM stage, the body is temporarily paralysed, which prevents people from acting out their dreams. This stage is associated with vivid dreaming and irregular breathing and eye movements. While the body is immobilised, the brain remains highly active, with brain metabolism increasing by up to 20%.

The body cycles between NREM and REM sleep throughout the night, with each cycle lasting around 90 to 120 minutes. A typical night's sleep consists of four to five sleep cycles, with the progression of sleep stages following the sequence: NREM stage 1, NREM stage 2, NREM stage 3, NREM stage 2, and finally, REM sleep.

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