Here’s What You Need to Know About the Stages of Sleep
Exploring the Complexities of Sleep: A Dive into NREM and REM Sleep Cycles
Sleep is a crucial part of our daily routine, yet many people still don’t fully understand it. In this article, we will dive into the findings of sleep expert, Mathew Walker, and explore the two stages of sleep, NREM and REM, and how they impact our brain and memory.
By the way, this is the second part of a series on sleep. See the first article: Why We Get Sleepy — And How To Manipulate It?
The Thalamus and Sensory Blackout
The thalamus is a part of the brain that acts as a sensory relay center. It processes and filters incoming sensory information from the body’s senses such as sight, touch, and sound. The thalamus decides which sensory signals are allowed to pass through to the cortex, the top part of the brain responsible for conscious perception, and which signals are not.
When we sleep, the thalamus locks its gates, preventing signals from reaching the cortex, and creating a sensory blackout. This is why we are no longer conscious of our surroundings while we sleep.
The Sleep Cycle: NREM and REM
The term “REM” stands for Rapid Eye Movement, and it’s named so because, during this stage of sleep, a person’s eyes move rapidly in different directions, even though the rest of the body is typically paralyzed. It’s a fun fact because it’s an interesting observation that our eyes can move so quickly during a stage of sleep when the rest of our body is immobile. This observation led to the discovery of the different stages of sleep and the important role that each stage plays in our overall well-being.
NREM just means non-rapid eye movement.
The two stages of sleep, NREM and REM, play out in a recurring pattern throughout the night. NREM sleep, which dominates early in the night, removes unnecessary neural connections in the brain. On the other hand, the later stage of REM sleep, with its vivid dreams, strengthens the bonds in our memory.
The sleep cycle is essential in helping us manage our memory storage and updating it every night with new experiences. This is why we require sleep each night to continue refining our memory networks.
Generating Sleep: Electrical Hallmarks of the Brain
When we are awake, our brainwaves are fast-frequency and chaotic. However, during NREM sleep, the brainwaves slow down and become far more synchronized and reliable. This state of deep NREM sleep is one of the most impressive displays of neural collaboration, with many thousands of brain cells firing in unison.
Deep NREM sleep helps transfer memories from a short-term storage site to a permanent, long-term location. This stage of sleep can be thought of as a time of inward reflection and information transfer.
In contrast, during REM sleep, the brainwaves return to their faster frequency and become desynchronized once again. This stage is characterized by the sensory gate of the thalamus opening and allowing signals of emotions, motivations, and memories to play out in our visual, auditory, and kinesthetic sensory cortices.
Information Processing: Wake, NREM, and REM
Wakefulness is primarily concerned with receiving and learning about the world around us.
NREM sleep is focused on storing and strengthening our new experiences.
And finally, REM sleep is a time of integration, connecting our raw experiences with one another and building a more accurate model of the world, including innovative insights and problem-solving abilities.
Why No Muscle Activity During REM Sleep?
One of the most interesting aspects of REM sleep is that muscle activity is eliminated during this stage. This is to prevent us from acting out our dreams, which can sometimes be dangerous.
Conclusion
Sleep is an essential part of our daily routine that has a profound impact on our brain and memory. Understanding the two stages of sleep, NREM and REM, and how they work together to update and refine our memories can help us appreciate the incredible power of sleep. Whether you are an expert or just someone who is curious about sleep, this article offers valuable insights into this fascinating subject.
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