The Science of Sleep: What Happens During Sleep

Sleep is vital to our survival. It promotes healing, encourages muscle growth and prevents disease. Improving your sleep is a way to extend longevity and take your health from average to excellent.

Understanding how sleep works and what our brain experiences while asleep can inspire us to prioritize rest and take our sleep quality to the next level.

This guide to the science of sleep covers what happens during sleep and how our bodies use the sleep cycle to repair and heal each night. We’ll also review the best ways to optimize your sleep cycle, including the most effective products for increasing comfort and reducing sleep disturbances.

Understanding the Brain’s Sleep Cycle

Sleep is not a static state. During sleep, the brain cycles through several rounds of different types of brain activity. These brain states make up the sleep cycle, which we all experience each night.

Here are some facts about the brain’s sleep cycle:

There are two types of sleep一REM (rapid eye movement) and non-REM sleep
The brain experiences 4-6 sleep cycles per night
A single sleep cycle is composed of four stages
Each sleep cycle lasts 90 minutes
How long each stage lasts depends on the cycle一early cycles are shorter and late cycles are longer
Each stage represents a different wavelength or level of activity in the brain

Below are the four stages of the sleep cycle.

Non-REM 1

The first stage of the sleep cycle is non-REM 1, which gets activated by the hypothalamus一the part of the brain that controls whether you’re awake or asleep. During this stage, the hypothalamus switches your body from an alert to a relaxed state. Many people experience twitches and jerks during this stage, which naturally occur as your body releases tension.

If left undisturbed, you can very quickly move from N1 to N2一normally within five minutes. Unless you get woken up at some point during the night, your brain probably won’t spend much more time in N1 throughout the remaining sleep cycles, if at all.

Non-REM 2

During N2, your body undergoes physiological adjustments to prepare for deeper sleep. Your heart rate and breathing slow, and your body temperature drops. Brain activity decreases, and eye movement stops.

Occasionally during N2, your brain may exhibit quick bursts of activity. Scientists say these sudden active states prevent you from being woken up by other stimuli like sounds, smells or your partner moving.

During the first cycle, N2 lasts up to 25 minutes, and time spent in this stage increases as the night progresses. Most people spend half the night in N2 across all cycles.

Non-REM 3

N3, also called deep sleep, is the most restorative stage of sleep.

While in N3, your brain produces delta waves, which are slow waves that cause the body to relax even further. Deep sleep is critical for healing the body and contributing to certain brain functions. It’s even associated with boosting the immune system.

We spend more time in deep sleep during the earlier cycles, with N3 lasting 40 minutes at its longest. As the night progresses, N3 stages get shorter so that you can spend more time in the final sleep stage一REM.

REM

Rapid eye movement sleep is the brain’s most active sleep state. While in REM, your muscles are temporarily paralyzed, with the exception of your eye and diaphragm muscles. REM sleep is associated with vivid and intense dreams.

The brain typically doesn’t undergo REM until you’ve been asleep for at least 90 minutes. The first few cycles of REM are often short and get longer in later cycles. The average person spends 25% of their sleep time in REM.

Getting enough REM sleep is critical for brain functions, including creativity, learning and memory.

3 Reasons Why We Need Sleep

We all know sleep is important. From our own experience, we find that the better we sleep, the better we feel. But why do we need sleep at all?

Brain scientists have different theories about the purpose of sleep, with the three main ones being physical restoration, waste elimination and memory consolidation.

1. Physical Restoration

During sleep, the body physically restores itself. The brain uses sleep to shut down the body so healing can take place. Not only does your body repair damaged tissues during sleep, but it also uses this daily rest period to grow stronger.

While in N3 and REM sleep, your body releases human growth hormone (HGH)一the protein responsible for building muscle, increasing bone density and regulating your metabolism.

Poor sleep interferes with HGH-release, among other vital hormones, which is why people with sleep disorders are at greater risk of obesity and other metabolic diseases.

Sleep also provides your body with an opportunity to conserve energy so you have more of it for the next day.

2. Waste Elimination

Throughout the day, your cells are highly active, performing numerous chemical reactions to keep your body functioning. However, these chemical reactions also produce toxic byproducts that accumulate in your body and need to be eliminated.

During sleep, your brain activates its glymphatic system一the network that clears away toxins from the central nervous system.

One of the most important toxins the brain discards during sleep is beta-amyloid一the protein that, when overly abundant in the brain, is linked to Alzheimer’s disease.

3. Memory Consolidation

Memory and learning are strongly interconnected一what you learn throughout life gets solidified in memory. The brain’s process for building memories, called memory consolidation, largely takes place during sleep. While resting, your brain processes what you learned from the day, parsing through your experiences and deciding which information to store where.

Memory consolidation is one of the most important purposes of sleep.

Inadequate sleep can cause you to forget things, leading to emotional frustration. Sleep deprivation makes it difficult to recall memories or access information you need, including basic coordination skills like driving a car.

Ways to Optimize Your Sleep Cycle

One of the biggest obstacles to getting a good night sleep is having your sleep-wake schedule interrupted. Whether you have a hard time falling asleep or you tend to wake up during the night, sleep disturbances can have ripple effects throughout daily life.

Monitoring your sleep quality helps you gain awareness of your sleep schedule and habits. If you notice that you’re not getting enough rest consistently, there are some doctor-recommended ways to get your sleep cycle back on track.

Below are three known ways to help optimize your sleep cycle:

Adopt Healthy Sleep Hygiene Habits

Sleep hygiene refers to the behaviors that promote vs. prevent sleep. To develop good sleep hygiene, it’s important to recognize how our habits contribute to how well we sleep.

Some examples of habits that affect the sleep cycle include:

Sleep-wake schedule一Going to bed and waking up at the same time each day synchronizes your daily schedule with your circadian rhythm, which is your internal clock.
Caffeine and alcohol一Limiting both substances throughout the day and not consuming them before bed prevents sleep disturbances.
Dinner time一Eating your last meal several hours before bed gives your body enough time to digest before sleep.
Daytime naps一Napping for no more than 30 minutes during the day prevents delaying your bedtime that night.

Adjusting just one or two of the above habits can lead to an improvement in your sleep quality and overall well-being.

Reduce Stress and Increase Relaxation

Stress is one of the biggest contributors to poor sleep. Research shows that stress decreases time spent in both deep and REM sleep一the two most important stages for restoration. Studies also found that high levels of stress increase the number of times you wake up during or in between sleep cycles.

To ease stress before bed, try developing a healthy bedtime routine that includes relaxing activities like taking a warm bath, reading a book or meditating. Avoid anything that will cause you stress before bed, such as checking emails or watching the news.

Upgrade Your Bed and Sleep Accessories

Your sleep environment, including your bed, can either help or harm your sleep cycle. It’s not uncommon for people to toss and turn at night because their bed or pillow doesn’t promote proper spinal alignment.

Tossing and turning can pull you out of your sleep cycle, preventing you from achieving the restorative sleep stages your brain needs.

Investing in good-quality bedding and sleep products is one of the best decisions you can make for your mental and physical health. Below are the top products that will help you achieve the ideal sleep setup for better quality rest:

Memory foam mattress: Providing a precise contour to your body’s shape, memory foam mattresses help relieve painful pressure points to minimize tossing and turning caused by discomfort.
Adjustable bed frame: Having the ability to adjust the top or bottom portion of your mattress allows you to find the perfect angle to reduce compression on your low back. An adjustable bed frame gives you the perfect mattress height for your comfort level so you can experience a disturbance-free night.
Ergonomic pillow: To keep your head and neck aligned throughout the night, you need a pillow that contours to the shape of your cervical spine. An ergonomic memory foam pillow will give you the support you need to prevent discomfort and promote deeper sleep.
Bedding and accessories: Top off your perfect bed setup with high-quality linens made from ultra-soft and breathable fabrics. Manage your body temperature throughout the night with a cooling topper to prevent overheating.

Shop Relax The Back for All Your Sleep Needs

Get the deep, healing sleep you need with the right sleep products from Relax The Back. Our selection of Tempur-Pedic mattresses and bases combined with our memory foam pillows and high quality Linens will help you personalize your sleep system for the highest quality rest possible.

Reduce tossing and turning and enhance your sleep cycle today. Visit a Relax The Back retail location near you to discover personalized sleep solutions.

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