What are Sleep Stages (Awake, Core, Deep, REM)?
Understanding your sleep stages is fundamental to interpreting your nightly sleep quality and its impact on your recovery. This guide explains the four main phases of sleep—Awake, Core, Deep, and REM—and clarifies the role each one plays in your overall well-being.
What the Sleep Stages Are
Throughout the night, your body cycles through different phases of sleep, each serving a unique purpose for mental and physical restoration. Our analysis breaks your sleep down into four key stages:
- Awake: It is normal to have brief periods of wakefulness during the night. These are often so short that you may not remember them in the morning. A small amount of awake time is a natural part of a healthy sleep cycle.
- Core (Light) Sleep: This stage makes up the majority of your total sleep time. During Core sleep, your body begins to relax, your heart rate and breathing slow down, and your body temperature drops. This phase is important for memory processing and helps prepare your body for deeper sleep.
- Deep Sleep: This is the most restorative stage for your body. During Deep sleep, your body works on physical recovery, repairing muscle tissue, strengthening the immune system, and promoting growth. Waking up from this stage is difficult, and you often feel groggy if you do.
- REM (Rapid Eye Movement) Sleep: This stage is critical for your brain. During REM sleep, brain activity increases, and most dreaming occurs. This phase is essential for consolidating memories, enhancing learning, and regulating emotions. It plays a key role in mental clarity and mood.
Why Understanding Sleep Stages Matters
Monitoring your sleep stages helps you move beyond just tracking sleep duration. It provides insight into the quality of your rest. By seeing how much time you spend in each stage, you can better understand why you might feel rested after one night but tired after another, even with similar sleep times.
A healthy balance of Deep and REM sleep is crucial for feeling physically recovered and mentally sharp. If you notice a consistent lack in these restorative sleep stages, it might be an indicator to adjust your daily habits, such as your evening routine or workout timing, to improve your sleep quality.
How It Works
The app estimates your sleep stages by analyzing data from your wearable device. It uses metrics like your heart rate, heart rate variability (HRV), respiratory rate, and body movement. Different patterns in these vitals correspond to the distinct physiological states of each sleep stage, allowing for an accurate breakdown of your night's rest.
Summary
This article defines the four sleep stages (Awake, Core, Deep, REM) and explains their unique functions. Understanding these stages allows you to assess your sleep quality more accurately, connecting the data to your daily energy levels and overall recovery.