Sleep is a complex process that is essential for our physical and mental health. During sleep, our bodies and minds go through a series of stages, including rapid eye movement (REM) sleep and non-REM (NREM) sleep.

NREM sleep is divided into three stages:

• Stage 1: This is the lightest stage of sleep and is characterized by a slowing of brain waves, heart rate, and breathing.
• Stage 2: This stage is characterized by further slowing of brain waves and heart rate, as well as muscle relaxation.
• Stage 3: This is the deepest stage of sleep and is characterized by very slow brain waves and muscle relaxation.

REM sleep is characterized by rapid eye movements, increased brain activity, and muscle paralysis. This is the stage of sleep where most dreams occur.

We cycle through these stages of sleep throughout the night, with each cycle lasting about 90-120 minutes. As the night goes on, we spend more time in REM sleep.

Here is a more detailed overview of each stage of sleep:

NREM Stage 1:

• This is the lightest stage of sleep and is characterized by a slowing of brain waves, heart rate, and breathing.
• It is easy to wake someone up from stage 1 sleep.
• This stage typically lasts for a few minutes.

NREM Stage 2:

• This stage is characterized by further slowing of brain waves and heart rate, as well as muscle relaxation.
• It is still relatively easy to wake someone up from stage 2 sleep.
• This stage typically lasts for 10-25 minutes.

NREM Stage 3:

• This is the deepest stage of sleep and is characterized by very slow brain waves and muscle relaxation.
• It is very difficult to wake someone up from stage 3 sleep.
• This stage typically lasts for 20-40 minutes.

REM Sleep:

• This stage is characterized by rapid eye movements, increased brain activity, and muscle paralysis.
• This is the stage of sleep where most dreams occur.
• REM sleep typically lasts for 5-10 minutes during the first sleep cycle of the night. As the night goes on, REM sleep periods lengthen.

We cycle through these stages of sleep 4-5 times per night.

Functions of REM and NREM sleep

REM sleep is thought to be important for memory consolidation, emotional processing, and creativity. NREM sleep is thought to be important for physical restoration and repair.

Both REM and NREM sleep are essential for good health. When we don’t get enough sleep, we can experience a variety of negative consequences, including fatigue, difficulty concentrating, and irritability.