4 Reasons Your Body Needs Deep Sleep (and How to Get More of It)

Deep sleep isn't just a phase we pass through at night – it's repairing, restorative, and fundamental to feeling invigorated and at our best each day.

While much attention has been given to the significance of REM sleep, the deep sleep stage, a segment of the non-REM cycle, holds tremendous benefits for our overall well-being. However, a deficit of this restorative sleep can lead to a myriad of problems, affecting our health, mood, and concentration.

So, what exactly is deep sleep, and how does it influence our lives? Dive with us into the realm of deep sleep as we explore its importance and share insights on how to maximize it.

 

What is deep sleep, exactly?

There are several stages in a sleep cycle, each playing a crucial role in ensuring a restful night. The initial three stages fall under the “non-REM” category, which stands for non-rapid-eye-movement sleep. Deep sleep is experienced during the third stage, often referred to as slow-wave sleep (SWS) or delta sleep. We’ll explore the others in the next section.

Delving deeper into the technical aspects, these waves have a frequency of 0.5 to 2 Hertz, and for a segment to be classified as deep sleep, these waves need to constitute at least 6 seconds of a 30-second window, as per a study mentioned on PubMed.

This stage is characterized by a slowdown in your heartbeat, breathing, and brain activity, leading to the feeling of being soundly asleep. Typically, one transitions into deep sleep about an hour after drifting off and undergoes gradually shorter durations of deep sleep as the night progresses.

The third stage can range from 45 to 90 minutes, with its duration diminishing with each successive sleep cycle. 

What are the stages of sleep?

Understanding the stages of sleep is essential for grasping the complexity and importance of a good night's rest. While we might simply think of sleep as a single, restful state, it's actually composed of various stages that cycle through the night. It generally takes about 90 to 120 minutes to complete a cycle of all the sleep stages. 

As a night progresses, adults will typically experience four to six of these cycles. Interestingly, the composition of these cycles changes as the night unfolds. During the initial hours, there's a dominance of NREM (non-rapid eye movement) sleep. As the night advances, there's an increasing prominence of REM (rapid eye movement) sleep, which becomes more extended with each subsequent cycle.

 

Stage 1

Often considered the gateway to sleep, Stage 1 is a fleeting phase where you find yourself drifting from wakefulness to slumber. In this drowsy segment, both your heartbeat and breathing undergo a gradual slowdown, setting the pace for the deeper stages that follow.

 

Stage 2

This is the phase of light sleep where the body undergoes more pronounced changes. As you delve deeper into relaxation, your heart rate and breathing continue to decelerate. There's a noticeable drop in body temperature and your muscles enter a relaxed state.

It's worth noting that as the night advances, Stage 2 sleep elongates with each cycle. In fact, nearly half of an average individual's total sleep duration is dedicated to this particular stage.

 

Stage 3

Often termed as the restorative phase, Stage 3 is the most profound segment in the sleep cycle. It's during this stage that the brain produces delta waves, which are slow in frequency but high in amplitude. This is the stage where the body undergoes extensive recuperation and rejuvenation.

 

REM (Rapid Eye Movement)

As the acronym indicates, during REM sleep, there's conspicuous movement of the eyes beneath the closed eyelids. Contrary to the relaxed state of the body, the brain is buzzing with activity, mirroring the patterns of an awake individual.

Though the brain is active, an intriguing aspect of REM is the general immobility of the skeletal muscles. It's widely accepted among experts that this stage hosts the majority of our vivid dreams.

 

NREM (Non-Rapid Eye Movement)

Initiating from the moment you drift off, NREM sleep encompasses the first three stages of the sleep cycle. Sequentially, the body transitions through these three NREM stages before reaching the REM phase. This progression ensures that the body gets the deep, restorative sleep it requires before entering the dream-rich REM sleep.

 

Who struggles with getting adequate deep sleep?

While the significance of deep sleep is clear, not everyone is fortunate enough to experience it in the desired amounts. Those who don't fulfill the recommended sleep duration often end up skimping on this vital phase, as deep sleep recurs several times throughout our resting period.

Interruptions in our sleep, whether due to disorders or disruptions in our sleep-wake rhythm, can also impede the body's ability to achieve adequate slow-wave sleep. Individuals suffering from insomnia, for instance, often grapple with altered sleep cycles.

This can lead to an extended duration of light, stage 1 sleep and a consequent reduction in deep sleep. Factors like stress and the inevitable aging process also contribute to diminished levels of deep sleep.

Recent scientific explorations have unveiled an intriguing connection between the brain's memory center, the hippocampus, and deep sleep.

  

What Are the Benefits of Deep Sleep?

While all of the stages of sleep are important to maintain good health, deep sleep offers a unique set of both mental and physical benefits for us.

 

1. Cognitive Function and Memory

Deep sleep is pivotal not just for basic memory retention but also enhances cognitive functions, language learning, fine-tuning motor skills, and nurturing the evolving brain.

As you navigate the day, your brain processes vast amounts of information, bolstering the synapses – the communication bridges in your brain's networks. But there's a catch: the brain can't keep assimilating information indefinitely without a breather. 

During deep sleep, your brain undergoes a selective filtration process. It assesses the myriad memories accumulated, retaining and fortifying the most pertinent ones, ensuring that memory pathways don't get overwhelmed. This mechanism is so precise that individuals often experience a surge in deep sleep after mastering a new task.

This heightened deep sleep is accompanied by pronounced slow-wave activity in the brain sections involved with the learned task.

 

2. Growth and Repair of Tissues and Bones

Deep sleep isn't just about mental rejuvenation; it's a pivotal time for physical recovery too. This is the phase when the body secretes growth hormones, spearheading the construction and mend of muscles, bones, and tissues.

Furthermore, deep sleep acts as a booster for our immune system, preparing it to fend off pathogens effectively.

3. Energy Restoration

One of the chief roles of deep sleep is energy revitalization. It amplifies the body's capacity to produce ATP, the fundamental energy molecule. As we plunge into deep sleep, the blood flow is redirected away from the brain, leading to a noticeable drop in its temperature. This process aids in energy conservation and preparation for the subsequent day.

4. A Boosted Immune System

Sleep doesn't just uplift our immune response; it also enhances the body's reaction to vaccinations. There's evidence to suggest that optimal sleep both before and after vaccination bolsters its efficacy, ensuring that our body responds best to the introduced vaccine.

 

What happens when you don’t get enough deep sleep?

Adequate deep sleep is essential for our well-being, and the absence of it can take a toll on various facets of our health. Not only does it result in feelings of fatigue and drowsiness, but it can also compromise various cognitive and physiological functions. Here's a closer look at the repercussions of an inadequate amount of deep sleep:

• Cognitive Impairments: Deep sleep is instrumental in the memory formation process. Without it, one might encounter challenges in consolidating memories from the day. This could lead to difficulties in recalling information or learning new things.
• Mental Fatigue: The rejuvenating effects of deep sleep are unparalleled. When deprived of it, one might wake up feeling unrefreshed and lethargic, making day-to-day tasks feel more daunting.
• Reduced Alertness: The ripple effect of insufficient deep sleep is evident in a reduced state of alertness. This might hamper the ability to focus on tasks or react quickly in situations that require immediate attention.
• Learning Difficulties: Deep sleep bolsters the brain's ability to assimilate new information. Without enough of it, there might be challenges in grasping new concepts or skills.
• Unhealthy Cravings: A disrupted sleep pattern, especially the lack of deep sleep, might lead to cravings for high-calorie foods. This can result in an unhealthy dietary pattern and potential weight gain over time.

 

Sleep Disorders Associated with Deep Sleep

Certain sleep disorders are intrinsically tied to the deep sleep stage. Known as disorders of arousal, these conditions can disrupt the restorative phase of sleep, leading to a range of symptoms.

The American Academy of Sleep Medicine (AASM) - a trusted organization dedicated to upholding standards and advancing excellence in sleep medicine - provides insights into these disorders.

While these disorders can affect adults, they are more pronounced in children and adolescents. This might be attributed to the developmental changes in sleep architecture experienced during these formative years.

In adults exhibiting symptoms of sleepwalking, there are noticeable differences in slow-wave activity during sleep. These variations in deep sleep patterns might hint at an underlying sleep disorder, further underscoring the importance of seeking medical advice if such symptoms persist.

 

How Much Deep Sleep Do You Need?

To grasp the amount of deep sleep one requires, it's essential to first understand the total amount of sleep needed.

For most adults, the recommendation is to target at least seven hours of sleep nightly. Of this, approximately 20% is typically spent in the deep sleep phase, as evidenced by recent studies.

However, the body possesses an innate ability to self-regulate the duration of deep sleep. For instance, after enduring a phase of sleep deprivation, you might observe a heightened period of deep sleep as the body attempts to recover.

On the other hand, habitual nappers might experience shorter durations of deep sleep during the night, given that a portion of their deep sleep requirement has been met during their daytime naps.

Age is another pivotal factor influencing deep sleep durations. As individuals advance in age, the proportion of deep sleep tends to decrease. In lieu of this, older adults often experience a more pronounced duration of stage 2 sleep.

 

How do you know how much deep sleep you’re getting?

To accurately gauge the amount of deep sleep you experience nightly, several physiological metrics can be monitored. Here are some ways to measure deep sleep: 

• Breathing Rate: Fluctuations or steadiness in breathing patterns can provide insights into various sleep stages.
• Oxygen Levels: Discrepancies in oxygen saturation may indicate periods of deeper sleep or disruptions like sleep apnea.
• Body Movements: Typically, deeper stages of sleep have limited body movement, while lighter stages or interruptions can involve tossing and turning.
• Heart Rate: During deep sleep, your heart rate usually slows down, making it a reliable indicator of this restorative stage.
• Brain Waves: The gold standard for measuring sleep depth is through electroencephalograms (EEGs) which monitor brain wave activity. Deep sleep is characterized by specific wave patterns, known as delta waves.

However, since most of us can’t measure these aspects on our own, subjective feelings upon awakening can also serve as valuable clues. If you consistently wake up feeling fatigued or unrefreshed, it might hint at a deficiency in deep sleep or disturbances during the night.

For those curious about tracking their sleep at home, wearable devices have become increasingly popular. These gadgets, such as smartwatches or fitness bands, primarily measure sleep based on body movement and sometimes heart rate. 

While these wearables can offer a broad understanding of your sleep patterns, they may not always provide a comprehensive or entirely accurate picture of deep sleep durations. It's crucial to interpret the data with a grain of caution and, if concerned about sleep quality, seek professional assessment for a more precise evaluation.

 

13 Ways to Get More Deep Sleep

Now that you know more about deep sleep, how can you get more of it? Here are some tips!

1. Exercising Regularly

Physical activity is linked to improved sleep quality. Even a simple daily walk can make a difference. However, try to avoid rigorous workouts close to bedtime as they might give you an energy boost when you least need it.

 

2. Reducing Caffeine Intake

Limiting caffeine consumption, especially in the afternoon and evening, can prevent disruptions in your sleep cycle.

 

3. Creating the Perfect Sleep Environment

A quiet, cool, and dark room can significantly enhance the quality of your sleep. Consider using blackout curtains, earplugs, or white noise machines if necessary.

 

4. Establish a Bedtime Routine

Routine actions can signal to your brain that it's time to wind down. Reading, light stretching, or listening to calm music can can help you set the tone for a peaceful night.

 

5. Take a Warm Bath

Warm baths or showers about an hour before bed can help induce sleep. As your body cools down post-bath, it signals the brain that it's time to rest.

 

6. Prioritize Sleep

Choose a bedtime that ensures you get the recommended amount of sleep for your age group. Consistency can help regulate your body's internal clock.

 

7. Stay Active

Beyond scheduled exercise, daily activities and movement can provide better sleep quality.

 

 

8. Opt for Natural Sleep Aids

While it may be tempting, long-term use of sleep medications can be counterproductive. Instead, explore natural options that may aid in sleep without the side effects.

Melatonin is naturally produced by the body and is sometimes known as the “sleep hormone” because it helps get us into a relaxed state that makes sleep come easier. But if you’re not getting the deep sleep you need, a melatonin supplement may be able to help.

Melatonin works pretty quickly, after just 30 minutes for many people. However, it doesn’t last long. Depending on the individual, it may only stay in the body for a few hours. So many will opt for controlled-release melatoninthat releases throughout the night. You can also combine controlled-release melatonin and CBD for maximum effect.

You get the added benefits of CBD — which is thought to play a role in helping your body’s endocannabinoid system regulate your sleep/wake cycle — and the controlled-release formula is thought to better mimic your body’s natural release of melatonin.

 

9. Limit Alcohol and Late Meals

Alcohol and large meals, especially close to bedtime, can disrupt your sleep. If you're hungry, opt for a light snack. Also, moderate your liquid intake to prevent nocturnal bathroom trips.

 

10. Dim the Lights and Electronics

Exposure to bright screens before bedtime can be stimulating and thus hamper your body's melatonin production, affecting your sleep-wake cycle. Consider screen filters or "night mode" settings on devices.

 

11. Stick to a Sleep Schedule

Consistency is one of the best things you can use to improve sleep. Try to sleep and wake at the same times every day, even on weekends. This consistency reinforces your body's sleep-wake cycle.

 

12. Try Binaural Beats

Listening to binaural beats, especially those mimicking delta waves, can potentially induce deeper sleep. Though research is ongoing, some people find them beneficial.

 

13. Ensure Sufficient Sleep Duration

Above all, ensure you're allocating enough time for sleep. Achieving the recommended hours for your age can enhance the proportion of time spent in deep sleep.

Incorporating these habits into your lifestyle can significantly boost your chances of enjoying restorative deep sleep. Prioritizing sleep ensures you're mentally sharp, emotionally balanced, and physically primed for the day ahead.

 

FAQs

Is 45 minutes of deep sleep enough?

While a study from the University of Warwick suggests that a 45-minute nap can offer benefits similar to a longer night's sleep, it's essential to understand that this doesn't replace the need for a full night's sleep.

For adults aged 18–60 years, the recommended sleep duration is 7 hours or more within a 24-hour period. Short naps can be beneficial, especially when trying to compensate for a lack of nighttime sleep, but they should not be a regular replacement for prolonged rest.

Which is better, REM or deep sleep?

Comparing REM (Rapid Eye Movement) sleep to deep sleep is like comparing apples to oranges; both are crucial for different reasons. Some individuals might feel more rejuvenated after a REM-rich sleep, while others might favor a deep sleep-filled night.

The key is to ensure a balanced sleep cycle, comprising both REM and deep sleep phases. Adjusting one's sleep environment or habits might help in achieving this balance.

What are slow brain waves?

During wakefulness, our brain activity is characterized by fast and irregular brainwaves. However, during deep sleep, or slow-wave activity (SWA), these brainwaves become slower and more synchronized. While it's believed that deep sleep initiates this slowed brain activity, comprehensive research is still underway to fully understand the connection.

What is a sleep debt?

Sleep debt refers to the accumulated difference between the sleep you've had and the sleep you ideally need. Over time, this deficit can lead to heightened fatigue, making it harder to function optimally during waking hours.

While trying to "pay off" this debt with extra sleep might help in the short term, studies indicate that prolonged sleep debt can have lasting effects on your metabolism and overall well-being. 

How much deep sleep is good?

The ideal amount of deep sleep varies from person to person, depending on factors like age, lifestyle, and overall health. While there's no universal "right" amount, ensuring you get a sufficient amount of deep sleep is crucial for physical and mental restoration. 

Does more deep sleep mean better sleep?

Quality sleep is more than just the duration; it's about the sleep cycle's composition. While deep sleep is vital for physical restoration, other sleep stages, including REM, are essential for cognitive functions like memory consolidation.

Striking a balance between these stages is key to achieving optimal sleep quality. Improving sleep hygiene and being mindful of one's sleep environment can potentially enhance the balance between different sleep stages.

 

Iris Goldsztajn is a London-based writer and editor with six years of experience creating content for various outlets. Her work has appeared in the likes of InStyle, Stylist and Cosmopolitan, and she won first place in Writing Magazine’s Grand Prize for a short story in 2020.

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