What are the stages of sleep and how many are there?

Achieving peak performance during the day starts with mastering your sleep at night. It’s a vital part of existence and an activity that takes up roughly a third of our lifetimes. 

But even though we can all agree sleep is so important, few people know the specifics of what’s really going on between the moment our head hits the pillow and the one when we open our eyes.

Sleep is a fascinating phenomenon that involves distinct phases — each serving different functions. In this article, we’ll go over the stages of sleep, discuss what happens in the body and brain during these sleep cycles, and explore why these unconscious processes are vital to maintaining your overall health. 

How many stages of sleep are there?

Many people grow up thinking of sleep in binary terms. On the surface, it can seem like there are only two states that we switch between: asleep and awake. 

However, the truth of sleep is not so black and white. Going to sleep is not simply flipping a switch “off” in the brain. Instead, sleep envelops high activity levels in the brain as well as measurable fluctuations throughout the body. 

So how many stages of sleep are there in total? Most scientists agree on four primary stages (or five if you count the state of being fully awake). Each stage serves a unique purpose, and they are all vital for maintaining your well-being. 

Stages of sleep

As we lay in bed and drift further into relaxation, we enter and move between different stages of the unconscious experience. 

Sleep cycle stages are broken down into two phases: -NREM sleep and REM sleep. 

The acronym REM stands for rapid eye movement. This term refers to the fact that your eyes actually make rapid twitching motions behind your closed eyelids during some parts of the sleeping process. 

The first three stages of sleep fall into the NREM (or non REM) category, while the final stage marks the point where these eye motions begin, accompanied by heightened levels of brain activity. Let’s take a closer look at these two primary phases of sleep architecture and what occurs while you’re in them. 

#1 N-REM Sleep 

Some scientists classify the intermediate space between being awake and falling asleep as the first official sleep stage. This stage consists of your eyes being closed for about 5 to 10 minutes. During this time of non rapid eye movement sleep, it’s usually pretty easy to be woken back up by a creaking floorboard or car horn outside.

#2 Light Sleep

While the previous, NREM stage of sleep is not much more than a transition between wakefulness and sleep, we have now entered the state of being fully asleep. 

This stage of light sleep lasts for 10 to 25 minutes and involves processes that prepare the body to enter deeper sleep. This part of the sleep process is marked by:

• Regulated breathing 
• Decreased heart rate
• Decreased body temperature 

About half of our total sleep time is spent in this stage. 

#3 Deep Sleep

At this point in the sleep cycle, you have descended deep into slumber and it becomes harder for outside stimuli to wake you up. 

This stage is crucial for allowing the body to repair itself. As you sink deep into uninterrupted restfulness, your body:

• Regrows tissues
• Bolsters the immune system 
• Builds bone and muscle 

During this stage, your muscle tone, pulse, and breathing rate all decrease while brain activity settles into patterns called delta waves. Brain activity is minimal during this period, but that doesn’t mean that deep sleep isn’t important for cognitive processes. 

On the contrary, evidence suggests that this intensive sleep stage is vital for:

• Creative thinking
• Memory processes
• Insightful thought

Also known as slow-wave sleep, the deep sleep pattern promotes health by releasing growth hormones, replenishing energy stores, and likely even preparing your synapses to learn new information the following day. 

#4 REM Sleep 

During this second phase of sleep, your eyes begin to move rapidly even though your lids are still closed. Additional indicators of REM sleep include:

• Brain waves that resemble those of wakefulness
• Quicker breathing and heart rate 
• Temporary paralyzation of the body
• The experience of dreams 

The reason why your muscles become limp during REM sleep is so that your body doesn’t act out your dreams. These very dreams are the explanation for increased brain activity during REM sleep. 

REM sleep accounts for about 25% of our total sleep time and serves vital functions such as:

• Long-term memory consolidation 
• Processing of new information 
• Improvement of mental concentration 
• Mood regulation 

How does the sleep cycle work?

Now that you’re more familiar with the individual sleep cycle stages, let’s take a look at how these separate elements come together to create a healthy, restful, and seamless night of slumber. 

You do not cycle through the stages of sleep just once before waking up. Instead, your body goes through several rounds of the cycle, up to about four to six times on a typical night.

An average singular cycle will last about 90 minutes in length, but the cycles often increase in length as the night goes on. Additionally, while you spend more time in deep sleep toward the first half of the night, REM sleep becomes more prevalent as time progresses. 

When each sleep stage is successfully cycled through, you are more likely to wake up feeling refreshed and full of energy rather than disoriented and dazed. 

Why is sleep so important?

The amount and quality of restorative sleep you experience every night plays a big role in how healthy, happy, and high-functioning you’ll be during your daily routine. 

You might think it’s no big deal to catch only a few hours of sleep or even skip it all together every now and then. However, the effects of sleep deprivation can be far more detrimental than you may think. 

Sleep loss and sleep disorders have been associated with increased risk of health consequences such as:

• Hypertension
• Obesity
• Depression
• Heart attack

The most obvious effects of poor sleep health you’ll immediately notice might be a dampened mood and irritating fatigue. However, in addition to having an adverse influence on your mental and cognitive functioning, a lack of quality sleep will negatively impact your cardiovascular, cerebrovascular, and metabolic health.

It’s clear that proper sleep is the foundation you need to build a successful life. When your sleep schedule starts to slip, your ability to function and perform daily responsibilities efficiently and effectively may begin to crumble. Improve your sleep and you’ll notice benefits in countless other areas of your life. 

How to get better sleep 

If you are experiencing occasional or chronic sleep issues, do not lose hope. There are strategies you can employ to prime your environment, mind, and body to enjoy higher-quality sleep.

Try out one or a few of these techniques to improve your chances of seeing a noticeable difference in your sleep quality: 

1. Tire yourself out – Exercising and staying active throughout the day will help you use up your energy so that you’ll feel more drowsy when nighttime arrives. When you can, try to avoid taking naps during the day, as this might negatively affect your ability to quickly slip into sleep when your actual bedtime arrives. 
2. Stick to a schedule – Our bodies like predictable, consistent routines. When you sleep at the same time every night, even when on vacation or on the weekends, you teach your body to recognize this pattern and grow tired at a specific hour. Committing to falling asleep at the same time each night will also help you achieve the proper recommended amount of sleep. Healthy adults should shoot for about 7 to 8 hours per night.
3. Adopt a pre-sleep routine – Much like a dog knows that a walk is coming when you pull out their leash, your body can recognize that sleep is approaching when you perform certain tasks. By creating a nightly regimen that leads up to the act of falling asleep, you can train your brain to wind down. This routine might include relaxing activities such as reading a book or taking a bath. 
4. Turn off the screens – Looking at bright devices such as TVs, computers, smartphones, or video game consoles near bedtime can make it difficult for you to fall asleep. The bright lights can trick your brain into thinking it’s still daytime. Furthermore, the content you’re consuming can impact your mental state. Whether funny videos are keeping you glued to your screen or news stories are increasing your anxiety, try to minimize scrolling before bed. 
5. Avoid eating or drinking before bed – While you don’t want intense hunger levels before bed, try to avoid last-minute feasts before you sleep. Heavy meals can cause stomach discomfort that can make falling asleep more difficult. Caffeine and alcohol are especially harmful to your sleep cycle, as their effects can take hours to wear off. 

With the help of these lifestyle tweaks, you can support your body in experiencing better sleep. Your body and mind will thank you (and reward you) for your efforts. 

Take control of your sleep quality with Apollo Neuro 

Sleep is a complex and marvelous process that our bodies undergo every night to replenish our systems and rejuvenate the mind. It’s important that you sleep deeply enough each evening to cycle through all the stages of sleep. 

When sleep problems become overwhelming and start interfering with your daily life, supplement your slumber with smart strategies and tools that can induce relaxation and promote a quiet seamless sleep experience. For that, Apollo is here to help. 

Among the many fine-tuned touch therapy vibrations that the Apollo wearable can provide, Fall Asleep is the top-used option employed by tens of thousands of people to improve their quality of sleep. Simply incorporate this device into your bedtime routine one hour before going to sleep to calm your mind and ease the body into high-quality sleep. 

Sources: 

National Library of Medicine. We spend about one-third of our life either sleeping or attempting to do so. https://pubmed.ncbi.nlm.nih.gov/21056174/

WebMD. What Are REM and Non-REM Sleep? https://www.webmd.com/sleep-disorders/sleep-101

John Hopkins Medicine. The Science of Sleep: Understanding What Happens When You Sleep. https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-science-of-sleep-understanding-what-happens-when-you-sleep

Sleep Foundation. Stages of Sleep. https://www.sleepfoundation.org/stages-of-sleep

National Heart, Lung, and Blood Institute. Sleep Phases and Stages. https://www.nhlbi.nih.gov/health/sleep/stages-of-sleep

National Sleep Foundation. What is REM Sleep? https://www.thensf.org/what-is-rem-sleep/

National Library of Medicine. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. https://www.ncbi.nlm.nih.gov/books/NBK19961/#:~:text=The%20cumulative%20effects%20of%20sleep,%2C%20heart%20attack%2C%20and%20stroke.

Journal of Clinical Sleep Medicine. Sleep is essential to health: an American Academy of Sleep Medicine position statement. https://jcsm.aasm.org/doi/10.5664/jcsm.9476

Mayo Clinic. Sleep tips: 6 steps to better sleep. https://www.mayoclinic.org/healthy-lifestyle/adult-health/in-depth/sleep/art-20048379