Unlocking the secrets of sleep: stages & optimal levels

Sleep stages are often an overlooked but crucial aspect of our lives. Getting enough quality sleep plays a significant role in our physical, mental, and emotional well-being. It can help your body repair and rejuvenate, support mental and emotional health, and improve memory and concentration. 

However, not all sleep is created equal, and understanding the different stages of sleep and optimal levels can help you get the most out of your rest.  In fact, just saying you slept seven hours doesn’t always mean you slept “well”. 

Now, I think the science is pretty clear that getting seven to eight hours of sleep nightly is important for overall health.  Although you may be “asleep” for seven to eight hours, different things are occurring during that time.  

Additionally, I highly recommend using simple sleep trackers to understand how well you’re sleeping.  For example, wearing your smart watch or fitbit while you sleep will provide feedback on each sleep cycle and length. 

So let’s take a deep dive into the four stages of sleep, how they influence your life and additional factors that can affect sleep quality. 

Sleep Cycles

First off, it’s important to understand that the process of sleep occurs in cycles, with each cycle lasting approximately 90 minutes in length. Each cycle includes all four stages of sleep, starting with the first stage and ending with REM sleep. 

Adults typically need seven to eight hours of sleep per night, which translates into around four to six sleep cycles a night.

Sleep Stage 1: Awake/Dozing Off (5-10 Minutes)

In the sleep cycle, the first stage is referred to as the transitional period between wakefulness and sleep. In this stage, you may feel like you are falling, experience fleeting thoughts, or experience muscle spasms. You may also experience a decrease in body temperature and heart rate. This stage usually lasts between 5-10 minutes.

Brain Activity During Stage 1 Sleep

When you enter stage 1 sleep, your brain activity begins to slow down from waking. Your brain waves transition from beta waves to alpha waves, indicating a decrease in mental activity. As a result of this decrease in brain activity, you are more likely to fall asleep.

Muscle Activity During Stage 1 Sleep

You also experience a slowdown in muscle activity during stage 1 sleep. During this stage, you may experience muscle spasms or twitches. This decrease in muscle activity helps your body relax and prepare for deeper sleep stages.

Eye Movement During Stage 1 Sleep

As you go into stage 1 sleep, your eye movements are slowed down. This is different from REM (Rapid Eye Movement) sleep, which is known as rapid eye movements. Your eyes may not move during stage 1 sleep, or they may move very slowly.

Importance of Stage 1 Sleep

Although stage 1 sleep is the shortest sleep stage, it still plays an important role in the sleep cycle. This stage prepares your body for deeper sleep by transitioning from wakefulness to sleep. If you do not undergo this transitional stage, falling asleep and achieving restful sleep may be more difficult for you.

Overall, stage 1 sleep is an essential part of the sleep cycle. A better understanding of sleep stages can help you prioritize your sleep and improve your sleep quality.

Sleep Stage 2: Light/Core (about 25 Minutes)

The second stage of the sleep cycle is called light sleep or core sleep. During this stage, you become more relaxed, and your body starts to prepare for a deeper sleep. Usually, this stage lasts from 25 to 30 minutes.

Brain Activity During Stage 2 Sleep

During stage 2 sleep, your brain waves continue to slow down from their waking state. However, you may experience brief bursts of higher-frequency brain activity known as sleep spindles during this period of sleep.

 The purpose of sleep spindles is to protect sleep by suppressing external noises and stimuli that could otherwise wake you up.

Muscle Activity During Stage 2 Sleep

In stage 2 sleep, your muscle activity decreases even further. In this stage, your muscles become relaxed, making movements more difficult.

Eye Movement During Stage 2 Sleep

Stage 2 sleep also slows down your eye movements. In fact, your eyes move slower than in stage 1, but they may still move a little bit.

Importance of Stage 2 Sleep

Your body transitions into deeper sleep stages during stage 2 of the sleep cycle. This stage helps your body relax and conserve energy for later use. You may feel groggy and tired during the day, having difficulty concentrating or completing tasks if you don’t get enough stage 2 sleep.

Sleep Stage 3: Deep (20-40 Minutes) sleep stage

Non-REM sleep is the third stage in the sleep cycle, which is the deepest stage of the sleep cycle. Your body is in a deep state of relaxation and repair at this point in the process. It usually takes between 20 and 40 minutes to complete this stage.

Brain Activity During Stage 3 Sleep

Your brain waves will slow down significantly during stage 3 sleep as compared to stage 2 sleep. During this stage of the process, you may experience very slow, deep delta waves. As mentioned earlier, these waves are associated with the deepest levels of sleep, and they help your body to recover and repair from the stresses and strains of the day.

Muscle Activity During Stage 3 Sleep

When you are sleeping in the third stage of sleep, your muscles are even more relaxed than they were when you were asleep in the first stage. As you enter this sleep stage, you may feel less sensitive to external stimuli, so you may have difficulty waking up from this stage.

Eye Movement During Stage 3 Sleep

During stage 3 sleep, your eyes do not move at all. This is because your body is in such a deep state of relaxation that it does not need to process visual information.

Importance of Stage 3 Sleep

Stage 3 sleep is an essential stage of the sleep cycle as it is the stage where your body is able to repair and recover from the stresses of the day. The body produces growth hormones during this stage, which helps to repair and rebuild tissues, strengthen your immune system, and build bones and muscles.

Your body may not be able to repair and recover adequately if you don’t get enough deep sleep, which can make you feel tired and irritable. It may also affect your immune system, making you more susceptible to illness.

Sleep Stage 4: REM (Lasts 10 Minutes)

The fourth stage of the sleep cycle is called rapid eye movement (REM) sleep. There is an increase in brain activity during this stage, and your eyes are moving rapidly back and forth behind your closed eyelids as if they are in a dream. 

When you are in REM sleep, you are typically experiencing the most vivid dreams as part of your sleep cycle. This stage usually lasts for about 10 minutes and occurs after all three stages of non-REM sleep.

Brain Activity During REM Sleep

In REM sleep, your brain activity increases to a level that is similar to when you are awake. However, your muscles are paralyzed, preventing you from acting out your dreams. You may experience irregular heartbeats, breathing, and body temperature fluctuations during this phase.

Eye Movement During REM Sleep

REM sleep, as the name implies, is characterized by rapid eye movements that occur during the restorative phase of sleep. 

Your eyes move rapidly during this stage, which can often be seen under closed eyelids.

Muscle Activity During REM Sleep

The muscles in your body are in a state of paralysis during REM sleep. This is to prevent you from physically acting out your dreams, which could potentially be dangerous.

Importance of REM Sleep stage

REM sleep is essential for maintaining optimal cognitive and emotional health. This stage involves the consolidation of memories and the processing of emotions in the brain. You can improve your mood, boost your creativity, and think more clearly if you get enough REM sleep.

If you do not get enough REM sleep, you may experience mood swings, difficulty concentrating, and memory problems. Mental health problems such as depression are more likely to occur when chronic REM sleep deprivation occurs for a prolonged period of time.

Optimal Levels

There are different levels of optimal sleep for each stage of sleep, which is very important to keep in mind when getting the recommended 7-8 hours of sleep each night. For example, if you want to achieve physical restoration and growth during deep sleep, then you should strive for 60-110 minutes of deep sleep every night. 

You can enhance the quality of your sleep by knowing the optimal levels for each stage of sleep so that you can keep track of your sleep and make improvements to it.

Factors that Affect Sleep Quality

Several factors can affect the quality of your sleep, such as caffeine intake and technology usage, meal timing. The stimulant caffeine can disrupt sleep, so it’s imperative to limit or avoid caffeine intake before sleep, especially before bedtime. The body takes around 8 hours to metabolize caffeine completely, so it’s crucial to be mindful of your caffeine intake throughout the day.

The use of technology can also affect the quality of sleep. Mobile devices emit blue light, which suppresses melatonin production. Melatonin regulates sleep-wake cycles. It is possible to delay sleep onset and reduce the quality of sleep when you use devices before bedtime. 

Sleep-tracking devices such as Apple Watches or Fitbits, or even Oura Rings, are a fantastic way to keep track of your sleep patterns and make sure your sleep hygiene is maintained.

Conclusion

Sleep is a fundamental aspect of our daily lives, and understanding the stages of sleep and optimal levels can help you get the most out of your rest. In general, adults need 7-8 hours of sleep per night, but the optimal levels vary by sleep stage. Sleep monitoring and aiming for optimal levels for each stage can help you unlock the secrets of sleep and lead a healthier, more restful life.