# data[].attributes.body
On average, we enter the REM stage approximately 90 minutes after falling asleep. The first cycle of REM sleep might last only a short amount of time, but each cycle becomes longer. REM sleep can last up to an hour as sleep progresses.

# data[].attributes.body
It is important to realize that sleep does not progress through these stages in sequence. Sleep begins in stage 1 and progresses into stages 2, and 3. After stage 3 sleep, stage 2 sleep is repeated before entering REM sleep. Once REM sleep is over, the body usually returns to stage 2 sleep. Sleep cycles through these stages approximately four or five times throughout the night.

# data[].attributes.body
REM sleep is also referred to as paradoxical sleep because while the brain and other body systems become more active, muscles become more relaxed. Dreaming occurs due to increased brain activity, but voluntary muscles become immobilized.

# data[].attributes.body
During REM sleep:

The brain becomes more active

Body becomes relaxed and immobilized

Dreams occur

Eyes move rapidly

Most dreaming occurs during the fourth stage of sleep, known as rapid eye movement (REM) sleep. REM sleep is characterized by eye movement, increased respiration rate, and increased brain activity.
The American Sleep Foundation suggests that people spend approximately 20 percent of their total sleep in this stage.

# data[].attributes.body
Older studies suggested that bed-wetting was most likely to occur during this deep stage of sleep, but some more recent evidence suggests that such bed-wetting can also occur at other stages. Sleepwalking also tends to occur most often during the deep sleep of this stage.

# data[].attributes.body
NREM Stage 3

During stage 3 sleep:

Muscles relax

Blood pressure and breathing rate drop

Deepest sleep occurs

Deep,slow brain waves known as delta waves begin to emerge during stage 3 sleep. This stage is also sometimes referred to as delta sleep.

During this stage, people become less responsive and noises and activity in the environment may fail to generate a response. It also acts as a transitional period between light sleep and a very deep sleep.

# data[].attributes.body
During stage 2 sleep:

People become less aware of their surroundings

Body temperature drops

Breathing and heart rate become more regular

lasts for approximately 20 minutes. The brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles. Body temperature starts to decrease and heart rate begins to slow.
According to the American Sleep Foundation, people spend approximately 50 percent of their total sleep in this stage.

# data[].attributes.body
NREM Stage 1

Stage 1 is the beginning of the sleep cycle and is a light stage of sleep. a transition period between wakefulness and sleep.
In Stage 1, the brain produces high amplitude theta waves, which are very slow brain waves.
Period lasts  around five to 10 minutes).
If you awaken someone during this stage, they might report that they were not really asleep.

# data[].attributes.body
“There are two main types of sleep:

1. Non-rapid eye movement (NREM) - also known as quiet sleep

2. Rapid eye movement (REM) - also known as active sleep or paradoxical sleep”

# data[].attributes.body
At the early stages of sleep the brain releases beta waves, which are small and fast. In the later stages when the brain starts to relax and claim down it starts to release alpha waves, which are slower waves.

# data[].attributes.body
“During the 1950s, a graduate student named Eugene Aserinsky used this tool (EEG) to discover what is known today as REM sleep.”

# data[].attributes.body
Cherry, Kendra, and Steven Gans. “The 4 Stages of Sleep (NREM and REM Sleep Cycles).” Verywell Health, Verywellhealth, www.verywellhealth.com/the-four-stages-of-sleep-2795920.