Body Systems

The Sleep Cycle

The Sleep Cycle
01

Meet The Sleep Cycle

We spend about 1/3rd of our lives sleeping, it is an important and normal body process that allows the body and brain to rest and recharge. When we sleep, our body, body systems, and processes all slow down, entering a state of rest. Did you know that certain essential processes occur during sleep? While we rest, our cells work to replenish and restore energy for the day ahead. The body focuses on healing injuries and repairing tissues. Meanwhile, the brain reorganizes, processes memories, and consolidates information that we have learned. This time is not a passive state; it’s an active time for our bodies and minds to recover and prepare. 

Stages of Sleep

While sleeping, the brain does not become totally inactive. Brain activity goes through predictable patterns or stages of sleep. These stages fall into two broad categories. Rapid eye movement or REM sleep and non-REM or NREM sleep. NREM sleep consists of deep restorative stages called slow-wave sleep or SWS. This is where physical repair and growth occur. REM sleep is where the brain processes and stores information, consolidates memory, regulates emotions, and regulates brain function. 

In each of these stages are cycles. There are three stages to NREM sleep. When we fall asleep, we enter NREM stage 1 and cycle between NREM stage 2 and 3. Stage 1 of NREM is the lightest stage of sleep and lasts only a few minutes. Stage 2 accounts for about 45% of sleep time and is slightly deeper than stage 1 but still considered light. This is where brain waves slow, and there are noticeable pauses in the brain’s electrical activity. We go through multiple rounds of NREM stage 2, each longer than the last. Stage 3 is the deepest stage of NREM and accounts for about 25% of sleep for adults. The brain is slow and strong in this stage, and the body uses it to repair injuries and reinforce the immune system. In stages 2 and 3, the brain has bursts of activity, and the brain waves in stage 3 regulate them. Stage 3 helps us to wake up feeling rested.

After stage 3, the next is stage 2 NREM, the doorway to REM. REM sleep accounts for 25% of sleep and is where dreams happen, and eyes tend to move behind the eyelids. Brain activity in this stage is similar to when we are awake! The first REM cycle is usually the shortest at about ten minutes. After the first REM cycle, you go into a new cycle and go back into stage 1 or 2, and then the cycle starts over. A cycle typically lasts between 90 and 120 minutes before another begins. Usually, people go through four to five cycles per night. 

The sleep cycle is complex and important. When we don’t get enough sleep in all the cycles, we go into a sleep debt, which is when the amount of quality sleep we get is not enough for what we need. When we don’t get enough sleep over long periods, we can’t catch up on the sleep we missed out on, which can lead to issues.

02

Anatomy & Function

How Much Sleep

So, what is enough sleep? How much sleep do we actually need? This varies from person to person and changes throughout our lifetime. Some people need less, and some people need more. Genetic, health, and environmental factors can all impact how much sleep we need. Due to hormones, females typically need more sleep than males, and that need can change throughout the menstrual cycle and pregnancy. 

Sleep doesn’t have to happen all at once! Sleep customs vary by culture and even time period. In some cultures, sleep is split into two periods during the night, and many cultures take napping seriously. 

The following is what is recommended and includes naptimes:

Age/Amount Needed

Birth to 3 months / 14-17 hours

4 months to 12 months / 12-16 hours

1 year to 5 years / 10-14 hours

6 years to 12 years / 9-12 hours

13 years to 18 years / 8-10 hours

19 years to 64 years / 7-9 hours

65 years and older / 7-8 hours

The Circadian Rhythm  

The circadian rhythm is our body's internal natural clock. This helps to regulate our natural and healthy sleep-wake cycle. This automatic process affects many processes in the body, ensuring they operate efficiently within 24 hours. This pattern or rhythm communicates to the body when it should sleep and when it should wake while also affecting hormones, digestion, and body temperature. This rhythm is set naturally and is controlled by the brain, specifically by a tiny cluster of cells called the suprachiasmatic nucleus or SCN located in the hypothalamus. The SCN is highly sensitive to light: when light enters the eyes, it signals the brain to stop producing melatonin, the hormone responsible for promoting sleep. While light plays a key role in regulating this rhythm, other factors such as food, stress, physical activity, temperature changes, changes to routine, travel, medication, mental health conditions, and poor sleep habits can all disrupt it. Disruptions in the circadian rhythm can negatively impact sleep quality and hinder the body's processes.

01

Meet The Sleep Cycle

We spend about 1/3rd of our lives sleeping, it is an important and normal body process that allows the body and brain to rest and recharge. When we sleep, our body, body systems, and processes all slow down, entering a state of rest. Did you know that certain essential processes occur during sleep? While we rest, our cells work to replenish and restore energy for the day ahead. The body focuses on healing injuries and repairing tissues. Meanwhile, the brain reorganizes, processes memories, and consolidates information that we have learned. This time is not a passive state; it’s an active time for our bodies and minds to recover and prepare. 

Stages of Sleep

While sleeping, the brain does not become totally inactive. Brain activity goes through predictable patterns or stages of sleep. These stages fall into two broad categories. Rapid eye movement or REM sleep and non-REM or NREM sleep. NREM sleep consists of deep restorative stages called slow-wave sleep or SWS. This is where physical repair and growth occur. REM sleep is where the brain processes and stores information, consolidates memory, regulates emotions, and regulates brain function. 

In each of these stages are cycles. There are three stages to NREM sleep. When we fall asleep, we enter NREM stage 1 and cycle between NREM stage 2 and 3. Stage 1 of NREM is the lightest stage of sleep and lasts only a few minutes. Stage 2 accounts for about 45% of sleep time and is slightly deeper than stage 1 but still considered light. This is where brain waves slow, and there are noticeable pauses in the brain’s electrical activity. We go through multiple rounds of NREM stage 2, each longer than the last. Stage 3 is the deepest stage of NREM and accounts for about 25% of sleep for adults. The brain is slow and strong in this stage, and the body uses it to repair injuries and reinforce the immune system. In stages 2 and 3, the brain has bursts of activity, and the brain waves in stage 3 regulate them. Stage 3 helps us to wake up feeling rested.

After stage 3, the next is stage 2 NREM, the doorway to REM. REM sleep accounts for 25% of sleep and is where dreams happen, and eyes tend to move behind the eyelids. Brain activity in this stage is similar to when we are awake! The first REM cycle is usually the shortest at about ten minutes. After the first REM cycle, you go into a new cycle and go back into stage 1 or 2, and then the cycle starts over. A cycle typically lasts between 90 and 120 minutes before another begins. Usually, people go through four to five cycles per night. 

The sleep cycle is complex and important. When we don’t get enough sleep in all the cycles, we go into a sleep debt, which is when the amount of quality sleep we get is not enough for what we need. When we don’t get enough sleep over long periods, we can’t catch up on the sleep we missed out on, which can lead to issues.

02

Anatomy & Function

How Much Sleep

So, what is enough sleep? How much sleep do we actually need? This varies from person to person and changes throughout our lifetime. Some people need less, and some people need more. Genetic, health, and environmental factors can all impact how much sleep we need. Due to hormones, females typically need more sleep than males, and that need can change throughout the menstrual cycle and pregnancy. 

Sleep doesn’t have to happen all at once! Sleep customs vary by culture and even time period. In some cultures, sleep is split into two periods during the night, and many cultures take napping seriously. 

The following is what is recommended and includes naptimes:

Age/Amount Needed

Birth to 3 months / 14-17 hours

4 months to 12 months / 12-16 hours

1 year to 5 years / 10-14 hours

6 years to 12 years / 9-12 hours

13 years to 18 years / 8-10 hours

19 years to 64 years / 7-9 hours

65 years and older / 7-8 hours

The Circadian Rhythm  

The circadian rhythm is our body's internal natural clock. This helps to regulate our natural and healthy sleep-wake cycle. This automatic process affects many processes in the body, ensuring they operate efficiently within 24 hours. This pattern or rhythm communicates to the body when it should sleep and when it should wake while also affecting hormones, digestion, and body temperature. This rhythm is set naturally and is controlled by the brain, specifically by a tiny cluster of cells called the suprachiasmatic nucleus or SCN located in the hypothalamus. The SCN is highly sensitive to light: when light enters the eyes, it signals the brain to stop producing melatonin, the hormone responsible for promoting sleep. While light plays a key role in regulating this rhythm, other factors such as food, stress, physical activity, temperature changes, changes to routine, travel, medication, mental health conditions, and poor sleep habits can all disrupt it. Disruptions in the circadian rhythm can negatively impact sleep quality and hinder the body's processes.

Supporting Systems and Interactions

The human body is a marvel of interconnected systems, each playing a vital role in maintaining balance, health, and vitality. While we often think of the body's organs and processes in isolation, the truth is that no part functions alone. Every system relies on and influences others in a delicate dance of cooperation.

When one system is compromised, others often compensate or respond, illustrating how deeply intertwined all functions are. The body, then, is not just a collection of parts, but an integrated whole, where every aspect plays a crucial role in maintaining the flow of life, energy, and healing. Understanding this interconnectedness allows us to approach health holistically, nurturing not just individual parts, but the whole person.

Sleep Comes Easily & Quickly To Me

Fun & Interesting Facts

  • Sleep is crucial for overall health and essential for learning memory, body repair, hormones, and brain function. It is as important as food, water, and air for survival
  • People can survive longer without food than they can without sleep
  • According to the CDC, staying awake for 24 hours has similar cognitive effects to a blood alcohol concentration of 0.10%, higher than the legal driving limit
  • Sleep deprivation is common, with about 40% of US adults and 70% of adolescents experiencing it
  • Humans are the only mammals that willingly delay sleep
  • Bright screens and artificial light can affect sleep cycles
  • Not everyone dreams in color, today 75% of people dream in color, but before color television, only 15% of people did
  • Sleepwalking affects about 6.9% of the population
  • Kids need more sleep than adults, and females need more sleep than males
  • Oneirophobia is the fear of nightmares or dreams, somniphobia is the fear of falling asleep, clinomania is the urge to stay cozy in bed all day, and dysania is when you wake up and don’t want to get out of bed. 

What is necessary for the optimal health of this system? 

Achieving and maintaining a balanced, healthy life requires a holistic approach that recognizes the complex interplay between nutrition, lifestyle, the use of herbs and supplements. Each of these elements plays a unique yet interconnected role in supporting the body's intricate systems.

Together, nutrition, lifestyle, and herbal support create a synergistic approach to health. They nurture the body as a whole, and support the body’s natural ability to heal, adapt, and flourish. Understanding the role each of these elements plays allows us to make more informed choices that contribute to lasting well-being.

Supporting Recipe

Cherry Lemon Balm Moon Milk

End your day on a calm and cozy note with this comforting bedtime beverage. Each ingredient in this recipe is thoughtfully chosen to help you relax and prepare for a good night’s sleep.

Lemon balm tea, known for its calming properties, helps ease stress and quiet the mind. Tart cherry juice provides a natural source of melatonin, supporting your body’s sleep-wake cycle. A touch of honey adds gentle sweetness, while warm milk creates a creamy, soothing base that feels like a hug in a mug.

This simple, delicious drink is the perfect way to wind down and transition into a restful night.

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About The Author

Shae Brackett our Customer Service Director and Social Media Manager, has been with RidgeCrest since 2016. Shae is a licensed massage therapist, and guides the customer care team, is our culture caretaker, and serves as our creative oracle across social media, blogs, and meditations. She describes herself as creative, thoughtful, nature-loving, compassionate, and nurturing. Her favorite herbs are Ginger and Lavender, and she proudly recommends SereniZen® (formerly Anxiety Free), PhysiQOL™, SinusClear®, and Belly Be Happy®.

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