We tend to think of sleep as a time when our body and brain simply shut off—but that couldn’t be further from the truth. Sleep is one of the most active and essential processes our body undergoes every day. It’s the ultimate reset button for our brain, body, and emotions.
If we want better energy, stronger mental health, and greater resilience, we must start by understanding what’s happening when our head hits the pillow. In this first blog of my eight-part RTJ Sleep Series, we’re diving into the science behind sleep—more specifically, the stages and cycles that shape the quality of our rest.
The Sleep Cycle: More Than Just “Light” and “Deep” Sleep
Each night, our body moves through a series of 90-minute sleep cycles, repeating the same rhythm several times. Within each cycle, there are four key stages—each playing a unique role in recovery, repair, and overall well-being.
Let’s break them down.
Stage 1: NREM 1 or N1 – The Transition Zone
Also called transitional sleep, this is the lightest stage. It lasts only a few minutes and often goes unnoticed.
- Your eyes begin to roll gently.
- Brain activity slows down as alpha waves begin to fade.
- Muscle activity decreases.
- You might twitch or feel like you’re falling.
Think of this as the doorway between wakefulness and true sleep. It’s brief but essential.
Stage 2: NREM 2 or N2 – Light Sleep
This stage makes up the largest percentage of our total sleep time.
- Heart rate and body temperature begin to drop.
- Breathing slows down.
- Muscles continue to relax.
- Your brain starts producing sleep spindles, little bursts of activity that play a role in memory and learning.
Though you’re more deeply asleep than in NREM 1, you can still be woken up easily.
⏱ Duration: Typically, 10–25 minutes per cycle, but increases in later cycles.
Stage 3: NREM 3 (and 4) – Deep Sleep / Slow Wave Sleep
This is the most physically restorative part of the night—what I call your body’s “repair mode.”
- Blood pressure and heart rate drop significantly.
- Breathing slows and stabilizes.
- Growth hormone is released.
- The body repairs tissues, builds bone and muscle, and strengthens the immune system.
It’s also very difficult to wake someone from this phase—and if you do, they’ll likely feel groggy and disoriented.
📌 Bonus Insight: Technically, what was once split into N3 and N4 is now grouped together as one “slow-wave sleep” stage. But understanding that this is your deepest, most essential form of rest is key.
REM – The Dream State
REM (Rapid Eye Movement) sleep is where your mind does its heaviest lifting.
- Brain activity spikes (often as active as when you’re awake!).
- Dreams occur here—sometimes vivid, emotional, or downright bizarre.
- The brain processes emotions, stores memories, and makes connections between experiences.
- The body experiences temporary muscle paralysis (a safety mechanism to keep you from physically acting out your dreams).
REM sleep first occurs about 90 minutes after you fall asleep and lengthens with each sleep cycle as the night progresses.
The Full Cycle: 90 Minutes of Restoration on Repeat
Your body moves through these stages in repeating 90-minute cycles throughout the night. The earlier cycles tend to have more deep sleep (NREM 3), while later ones lean more into REM. That’s why a full night’s sleep—ideally 7 to 9 hours—isn’t just about quantity. It’s about cycling fully and smoothly through these stages.
Why This Matters for Your Health and Resilience
Understanding these stages isn’t just academic—it’s practical.
If you’re cutting your sleep short, waking up frequently, or having poor sleep quality, you’re not giving your body the full chance to go through the stages that help you:
- Store and consolidate memories
- Heal and repair muscle
- Process stress and emotions
- Strengthen your immune system
- Maintain focus and performance throughout the day
What’s Next?
This blog is just the beginning. Over the next few weeks, I’ll be sharing more insights from my sleep coaching toolkit—from the science behind circadian rhythms to real-life strategies that improve sleep hygiene and stress recovery.
If you found this helpful, stay tuned for the rest of the RTJ Sleep Series. And if your workplace or team is struggling with sleep, stress, or burnout, reach out—RTJ Wellness offers workshops and coaching designed to build healthier habits and more resilient lives.
Because when we sleep well, we live better.
—
Rob Jetten
Certified Sleep, Stress & Resilience Coach
Owner – RTJ Wellness