Understanding the three main stages of sleep
Your sleep is made up of distinct stages, each supporting different physical, mental and emotional processes.
Every night, your body cycles through light sleep, deep sleep and REM sleep several times. Each stage has a specific function, and interruptions to these stages can impact mood, memory, energy levels and overall health. Discovery's Sleep Factor white paper explains that good sleep is not only about quantity but also about the quality of these cycles.
Light sleep prepares the body for deeper stages, deep sleep focuses on recovery and repair, and REM sleep supports emotional regulation and memory consolidation. A disruption in any one of these areas can leave you feeling less restored, even if you slept for the right number of hours.
These stages shift throughout the night. Deep sleep dominates the first half, while REM sleep increases in the early morning hours. Consistent routines, stress management and good sleep hygiene help protect these cycles, ensuring you get the benefits of each stage.
"Good sleep is not only about time spent asleep. Each sleep stage performs a unique function, and disruption at any stage affects how you feel the next day," says Dr Mosima Mabunda, Chief Clinical Officer at Vitality.
The three main stages of sleep
1. Light sleep
Light sleep marks the transition from wakefulness. Heart rate and breathing slow, muscles relax and responsiveness to external stimuli drops.
Key functions:
- Begins memory encoding,
- stabilises the nervous system,
- sets up the deeper restorative stages to follow.
2. Deep sleep (Slow Wave Sleep)
Deep sleep is when the body does its heaviest repair work.
Key functions:
- Physical tissue repair,
- immune system strengthening,
- metabolic regulation,
- supporting healthy blood pressure and glucose control.
Most deep sleep occurs in the first half of the night.
3. REM sleep
REM sleep features vivid dreaming and increased brain activity.
Key functions:
- Emotional regulation,
- learning and memory consolidation,
- creativity and problem-solving.
Most REM sleep occurs in the second half of the night.
Balanced light, deep and REM sleep ensures you wake feeling restored. Interruptions early in the night reduce deep sleep, while late-night disruptions affect REM. Poor sleep quality over time increases chronic disease risk and reduces cognitive performance.
Understanding these stages helps you identify what may be affecting your sleep quality and where to focus your habits.
Do you want to learn how you can sleep better naturally? Here are eight tips that will help improve the quality of your sleep: >https://www.discovery.co.za/vitality/sleep-better-naturally.