
If you’ve ever woken up after a full night’s sleep not feeling quite as rested as you should, it may not be how much sleep you’re getting, but the quality of sleep. Not getting enough quality sleep can leave you feeling unrested, unfocused or generally just not your best.
Moving through the different stages of sleep smoothly is key to getting a good night’s sleep. With each stage playing a part in helping you wake up feeling refreshed, it’s important to understand the entire sleep cycle.
Let’s explore the different sleep stages and how you can get the best night’s rest each night.
What happens when we sleep?
Sleep is sleep, right? Well, not quite.
When you close your eyes to go to sleep, your body enters a sleep cycle made up of different stages. You’ll generally go through four to six sleep cycles during each rest period, cycling through two types of sleep and four different stages. Each cycle may be a different length, although typically they last around 90 minutes each1.
What are the different sleep stages?
There are four different sleep cycle stages; N1 or wakefulness, N2 or light sleep, N3 or deep sleep and REM sleep. They are often categorised as two types of sleep, non-rapid eye movement (NREM) which includes cycles 1 to 3, and rapid eye movement (REM) sleep1.
NREM sleep
Non-rapid eye movement sleep is also called non-REM or NREM. It’s known as the restful phase and includes the first three stages of the sleep cycle.
In the non-REM sleep cycle, you fall asleep, ease into a light sleep and then shift into a deeper sleep. As you move through these three cycles, your brain activity, breathing and heart rate slow down, body temperature drops, muscles relax and your eye movements stop, allowing you to enter the deepest stages of sleep and rest2.
While REM sleep is often the type of sleep people focus on, NREM sleep is equally as important. This is where your body repairs tissue and strengthens the immune system, as well as builds bone and muscle2. It’s also where your brain gets to work consolidating memories, helping them become long-term memories, also helping you remember new skills. It’s one of the reasons NREM sleep is so important, as it optimises your brain for future learning, crucial for all stages of life, young and old3.
Stage 1 (N1) - Falling asleep
The first stage of the sleep cycle is one you’re likely very familiar with; falling asleep. It is the lightest stage of the sleep cycle where your brain starts to slow down, with alpha brain waves swapping places with low-amplitude mixed frequencies (LAMF), causing you to become drowsy4,5.
As your body makes these lighter changes to fall asleep1, your body isn’t fully relaxed, with muscle tone remaining present in the skeletal muscle, and breathing becoming more regulated4. You’ll typically be in stage one for around 1 to 5 minutes, making up 5% of your total sleep time4.
Stage 2 (N2) - Light Sleep
Once you fall asleep, your body moves into stage 2 of the sleep cycle; light sleep.
In this deeper state of sleep, your heart rate and body temperature drop lower4, and your muscles become more relaxed as your breathing slows down1. Your brain actually shows a new pattern as its activity decreases, and your eye movement also stops in this stage1.
Typically, stage two will last around 10 to 25 minutes in the first sleep cycle. Then, it will lengthen with each cycle of the stage to a combined length of about 45% of your total sleep time4.
Stage 3 (N3) - Deep Sleep
Stage 3 of the sleep cycle is your deep sleep stage, also known as slow-wave sleep (SWS)4. It’s typically the deepest stage of sleep and the most difficult to be woken from4.
So, what is deep sleep? This stage is thought to be the most critical stage for restorative sleep1. This is when your body really gets to work repairing itself and regrowing tissue, building bone and muscle and strengthening your immune system4. It’s also a key time for your brain, with cognitive testing showing that people who are woken up during this stage tend to have moderately impaired mental performance, lasting for anywhere between 30 minutes to 1 hour4.
REM Sleep
You may know rapid eye movement as your dream state4, but what is REM sleep? This stage starts roughly 90 minutes after your sleep state, with cycles ranging between ten minutes to one hour, extending with each cycle4.
While it’s true that REM sleep is when you have most of your dreams, it is not considered a restful sleep stage4. Instead, your brain is actually very active during this stage of sleep, increasing brain metabolism (or energy) by up to 20%4. Your breathing rate is more erratic and irregular4.
However, this stage of sleep is crucial in your brain consolidating and processing new information that it’s taken in throughout the day. REM is also important for improving your mental concentration and also your mood6 - both of which are crucial to your overall well being.
How long is a sleep cycle?
It’s important to know that every sleep cycle is different. However, generally you’ll go through anywhere from four to six sleep cycles, with the average sleep cycle length being 90 minutes.
Your sleep cycle length will also change as you progress through the night. The first cycle is typically the shortest at around 70 to 100 minutes, while your last cycle is the longest, between 90 to 120 minutes1, on average. This may also change night-to-night depending on your sleep patterns or even if you’ve consumed alcohol1. Plus factors like age and sleep disorders can also impact it.
How much deep sleep is normal?
Generally, you’ll need around 1.5 to 2 hours of deep sleep4 - that’s around 20% of your time in bed. This is based on a healthy adult requiring at least 7 hours of sleep6 each night.
However, you may not need to be too concerned about how much deep sleep you’re getting each night. This is because your body will actually regulate deep sleep on its own. For example, your body may spend more time in a deep sleep stage if you haven’t been sleeping well lately, or spend less time in this stage if you have had a nap and had your deep sleep needs met already3.
How much REM sleep do you need?
The average, healthy adult will need around 2 hours of REM sleep each night. That means if you sleep seven to eight hours per night, that’s 25% to 28% of your total night’s sleep. While this stage is where you dream the most, it’s also critical for your brain development and emotional processing, helping you retain long-term memories5.
What is the more restful stage of sleep?
The non-REM stages of sleep, particular stage 3 (deep sleep) are considered the most restful than REM. Stage 3, or deep sleep, is an important stage of restorative sleep and is vital for helping you think, be more creative and to improve your memory1. Stage 4 also plays an important role in your cognitive function and helps with things like memory, learning and creativity.
However, at the end of the day, all four stages of sleep are important, with each playing their own role in helping your mind and body to feel refreshed in the morning1.
How to get more deep and REM sleep
With all this in mind, you might be wondering how to get quality sleep each night. There are many ways to help get a deeper sleep, including:
- Going to bed at the same time each day.
- Managing your stress levels.
- Avoiding alcohol, caffeine and tobacco.
- Maintaining a comfortable bedroom for ideal sleep conditions.
- Following good sleep hygiene.
- Avoiding medication, where advised by a medical professional, that can suppress REM sleep7,8.
Remember that your body does a good job at regulating your sleep, so the best way you can help it is by ensuring you get enough sleep each night, allowing your body to move through the different stages of the sleep cycle.
Looking for more information about sleep? The Swisse Wellness Hub is full of information to help you learn more about ways to improve your sleep, including the impacts of sleep hygiene, links between sleep and immune health, and more.
References:
- Suni, E., & Suni, E. (2023g, December 8). Stages of sleep: What happens in a sleep cycle. Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep
- Patel AK, Araujo JF. Physiology, sleep stages [Internet]. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK526132/
- Pacheco, D., & Pacheco, D. (2023b, November 3). What is NREM Sleep? Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep/nrem-sleep#:~:text=During%20NREM%20sleep%2C%20the%20brain,motor%20learning%2C%20and%20word%20retrieval.
- Patel, A. K., Reddy, V., Shumway, K. R., & Araujo, J. F. (2024, January 26). Physiology, sleep stages. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK526132/
- Summer, J., & Summer, J. (2024b, March 22). REM Sleep: What It Is and Why It’s Important. Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep/rem-sleep
- Thensf. (2024, September 5). What is REM Sleep? National Sleep Foundation. https://www.thensf.org/what-is-rem-sleep/
- Rausch-Phung, E., & Rausch-Phung, E. (2024, March 22). How to get more deep sleep: Tips for a restful night. Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep/how-to-get-more-deep-sleep.
- Noyed, D., & Noyed, D. (2024, April 15). 5 ways to get more REM Sleep. Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep/how-to-get-more-rem-sleep