REM Sleep vs Deep Sleep : Differences Worth Knowing

Sleep is essential for good health and well-being. When you sleep your body gets enough rest to heal and restore energy. While adequate sleep is important, good sleep at night can help to cope with stress, recover from illness and solve problems.¹

Many things happen when you sleep and you pass through various stages of sleep. Your sleep cycle begins with non-rapid eye movement, which includes the deep sleep stage, and then you enter the rapid eye movement phase. Here, we will try to understand REM sleep vs deep sleep.

REM sleep, or Rapid Eye Movement sleep, is a stage of sleep characterized by rapid movement of the eyes, increased brain activity, and vivid dreaming.

Deep sleep, also known as Non-REM stage 3 sleep, is characterized by slow brain waves and a lack of movement or muscle activity.

Before we discuss REM sleep vs deep sleep in detail, it is important to know the various stages of sleep. The sleep stages are the natural cycles of activity that your brain goes through when you sleep. There are four stages of sleep, which are divided into two phases.

The two phases of sleep include:

NREM (non-rapid eye movement), is further divided into three stages (N1 to N3) – The last two stages are deep sleep, from which it is difficult to wake up and which offers various health benefits.

REM (rapid eye movement) – This is the stage of dreams and happens about an hour or hour and a half after falling asleep.

REM sleep vs deep sleep shows variations in brain activity levels, Electroencephalogram (EEG) patterns, and functions.

In every phase and stage of sleep, brain wave patterns, eye movements, and muscle tone changes are noted. Each cycle takes about 90 minutes and the body cycles through these stages about 4 to 6 times in a night’s sleep.²

As the NREM sleep progresses into the next stage, you move into a progressively deeper sleep. You spend 75% of your sleep in the NREM stages, which include the deep sleep stage. During a night sleep, the sleep process is cyclical and with the onset of sleep, there is a rapid descent to the deep sleep stage (N3) within the first hour. Following this, the phase of NREM and REM alternate every 60 to 90 minutes throughout the rest of the night.³

Let us look at the variations in each sleep stage that also explains REM sleep vs deep sleep.

Stage 1 (N1) – A part of NREM, is a drowsy period when you begin to move from the awake state towards falling asleep. Your body functions like respiration, muscle activity, eye movements, and heartbeat begin to slow down. Your muscles begin to relax with some twitches. If you wake up from this stage, you may feel as if you haven’t slept at all. The EEG recordings show theta waves. The frequency begins to reduce and the amplitude of the cortical waves begins to slightly increase. This stage lasts for about five minutes and comprises about 5% of total sleep time.²

Stage 2 (N2) – During this stage, your heart rate further slows and body temperature further decreases. In this, stage of light sleep there are periods of muscle partially contracting and relaxing.

This stage prepares your body to enter the deepest sleep. Brain waves slow down as there is a further decrease in the frequency of EEG waves. As the increase in the amplitude with high-frequency spike clusters is noted, often termed sleep spindles may be noted. Sleep spindles are periodic bursts of activity of about 10 to 12 Hz that may last for 1 or 2 seconds.⁴

This sleep stage is one of the deeper states with long delta waves and helps maintain sleep and memory function. Teeth grinding may occur during this stage. It lasts for about 25 minutes during the first cycle and its duration increases in the successive cycles, such that it comprises about 45% of your sleep.²

Stage 3 (N3) Deep Sleep – This is the deepest sleep stage, during which delta waves of lower frequency of about 1 to 4 Hz and higher amplitude are produced. There is no eye movement or muscle activity. This is commonly called deep sleep, from which it is difficult to wake up someone. Some people may not be able to wake up even in the presence of loud noises.

If you are made to wake up during this stage you may experience mental fogginess or sleep inertia, which can make you feel disoriented for some time after waking up. Studies have shown that when people are awakened during this stage, they may have impaired mental performance for 30 minutes to an hour.²

Sleepwalking, night terrors, and bedwetting may also occur during the deep sleep stage. With aging, some people may spend less time in the deep sleep stage than younger people.

The deep sleep stage is the most important as it promotes healing, repair, and growth. It promotes the secretion of certain hormones that are required for physical and mental well-being.

Studies have shown that sleep efficiency, sleep time, and deep sleep decrease with aging, and the number of awakenings at night and time spent staying awake at night increase. This may have an impact on the circadian rhythm, sleep-related hormones, and overall health of the aging population.⁵

Studies have reported that the growth hormone levels increased significantly during the deep sleep stage as compared to stages 1 and 2 and REM sleep.⁶

Experts have also found that when deep sleep was suppressed for three consecutive nights, the insulin sensitivity decreased, thus reducing glucose tolerance and increasing the risk of diabetes.⁶

REM Sleep – This is a stage of rapid eye movement or REM sleep. Following the stage of deep sleep, the stages of sleep reverse to a different state, and the EEG recordings in REM sleep are similar to that of the awake state.4 This means that soon after deep sleep you enter the REM sleep in which your brain activity again increases and the sleep is not as deep.

• During the REM sleep
• there is rapid eye movement from side to side
• the major muscles that are normally controlled are unable to move and you may even feel as if they are temporarily paralyzed
• heart rate increases and breathing may become faster as the brain activity increases
• you may have vivid dreams during REM sleep

Your first REM sleep is short of about 10 minutes and as the night sleep progresses you will have longer REM sleep and shorter deep sleep. In your lifetime, the amount of REM sleep often changes as you age. REM sleep is noted to be the highest during infancy and early childhood, after which it begins to decline during adolescence and young adulthood and further declines even more as you grow old.

REM sleep helps stimulate the areas of the brain that are involved in learning and is also associated with increased production of proteins.⁷ Thus REM sleep is equally important as it promotes learning and memory.

REM sleep offers benefits like:

• Enhanced learning
• Better memory
• Emotional well-being

The benefits offered during the deep sleep stage include the following:

• The body repairs and heals,
• Promotes better growth and health,
• Regrows tissues,
• Builds bone and muscle,
• Strengthens the immune system

Your sleep cycle takes you through light sleep, deep sleep, and REM sleep and all stages are very important for your health and well-being. Sleep disruptions or lack of adequate sleep can affect the circadian rhythm, and imbalance of hormones and increase the risk of metabolic disorders, insulin resistance, weight gain, and diabetes.

REM sleep and deep sleep both offer different benefits and are equally essential parts of your sleep cycle. If you do not sleep well at night or if your sleep is interrupted, your sleep cycle is affected. In such cases, you will not be able to get the benefits of these sleep stages, affecting your physical and mental health. Hence, it is important to sleep well at night to experience both deep sleep and REM sleep and allow the smooth cyclical progression of sleep throughout the night.

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