What Happens When You Sleep?

Intro

Have you ever been curious as to how our mind and body react to sleep? The process of falling asleep, and staying asleep, occurs through different stages of sleep, also known as sleep cycles. Understanding how these sleep cycles work is critical to how we approach certain sleep disorders, such as insomnia and sleep apnea. Not only would you appreciate sleep more, but we hope that it will help improve how you sleep in the future.

Stages of sleep

There are two phases of sleep we go through: rapid eye movement (REM) sleep and non-REM sleep. Since everyone's sleep schedule is different, not everyone will experience the same length or quality of sleep in each stage. Our sleep cycles can also vary in length, depending on the time we go to bed or distractions we have in our environment (i.e. sound, light, etc.).

The average adult will experience four to six stages of sleep in a given night. Each stage will progress differently, but typically REM sleep is achieved about 90 minutes after falling asleep. REM sleep is the most important stage of sleep since it stimulates memory retention. It also strengthens our brain's neural connections, which improves our ability to learn and recall complex material.

The cycle of sleep

Although the stages of sleep are numbered, they do not happen in succession. Instead, some stages repeat throughout the night. Sleep starts at Stage 1, and progresses through Stages 2 through 3. At about 20 - 30 minutes into sleep, Stages 2 or 3 repeat again before your mind and body enters REM sleep.

After REM sleep, your body will revert back to Stages 2 and 3 (non-REM sleep). The average adult will continue through this sleep cycle at least 4 or 5 times a night, depending on how well he or she sleeps. Typically, the first couple of cycles is the shortest, while the last few cycles are the longest.

Non-REM sleep

Stage 1 is the lightest stage of sleep you'll experience. Breathing and muscle tone are about the same as if awake, however they'll begin to slow down as you transition to deeper sleep. This stage usually lasts 1 to 10 minutes. If you sleep with a partner, take care not to wake them, since they can be easily awoken.

Stage 2 is where your heart rate, breathing, and muscle tone begin to relax. Your body temperature also begins to drop as your metabolism slows down. At this stage, your brain fully transitions to deeper sleep. Brain patterns shift completely to show occasional bursts of activity, known as "sleep spindles". This type of brain activity helps you stay asleep by ignoring sounds from your environment. Stage 2 is where you'll spend most of your time asleep during each sleep cycle.

Stage 3 is progressively the deepest part of sleep you'll experience during the night. At this point of time, your body begins to repair itself, which helps keeps your immune system strong. Your heart rate and breathing is also at its lowest, since little energy is needed to maintain bodily functions. This stage of sleep also contributes to memory retention and creativity. As your sleep cycle progresses, you'll spend less time in this stage of sleep.

REM sleep

Stage 4 occurs 90 minutes into sleep, and is known for its rapid eye movement seen under the eyelids. This is because your brain activity increases to levels near wakefulness, allowing more vivid dreams to take place than in other stages. Your breathing and heart also increases, however your muscles are still paralyzed to keep you from "acting out" your dreams. In the average adult, REM sleep amounts to 25% of total sleep.

REM sleep also helps with memory retention and recall. Since our brain activity increases, this helps us process and restore what we learned from the day prior. That being said, it is very important for our minds to engage in this stage of sleep, especially the second half of the night where REM sleep is at its longest. After REM sleep, you'll transition back to Stage 2, then repeat the cycle over again.

Sleep changes as we age

The length of sleep decreases the further up you move in age. In other words, the older you get, the less sleep you require. Since we spend most of our life as adults, we typically need at least 7 hours of sleep a night. Everyone is different though, so some might require more or less hours of sleep. As we age, our REM sleep is gradually reduced. In fact, we get the most REM sleep when we're babies! Teenagers need at least 7 - 9 hours of sleep. During your golden years, you'll need about the same 7 - 9 hours of sleep each night.

How to get good sleep

Getting good, quality sleep is important if we are to function at our optimal selves each day. Not only is it good for our brain, but it is also good for our entire body. Sleep recharges us, helps us retain memories, and allows us to repair ourselves at the cellular level. If you're experiencing a lack of sleep, consider your mattress! If you have an old mattress, read our article on when to replace your mattress. If you're looking for a new mattress instead, we have our mattress buying guide for you to read.



Your ideal sleep environment is also important. Practicing good sleep hygiene (or habits) is also a must. While a good sleep environment prepares you to sleep, good sleep habits help you stay asleep. Both go hand-in-hand however, so don't ignore one over the other. There are also other topics in our blog that can help you improve your sleep today, such as our pillow buying guide, how to break in a new mattress, or common mattress types. Take your time through them and see how your sleep can improve over time!