What Happens During The Different Stages Of Sleep?

What Happens During The Different Stages Of Sleep?

Most of us think about sleep in terms of hours. Did you get your seven or eight? But how long you sleep is only part of the story. What actually happens while you're asleep matters just as much, and that comes down to the different stages your body and brain move through each night.

Every night, you cycle through four distinct sleep stages, usually several times over. Each stage plays its own role in helping you wake up feeling genuinely rested, rather than just having clocked enough time in bed.

The Journey Through A Sleep Cycle

A full sleep cycle takes around 90 minutes, and most people move through four to six of these cycles a night.¹ The first cycle tends to be a little shorter, while later ones stretch out longer. As the night goes on, the amount of time spent in each stage shifts too, which is why the sleep you get earlier in the night looks quite different from the sleep you get just before waking.

Stage 1: Drifting Off

This is the lightest stage of sleep, and it happens the moment you first nod off. Your body hasn't fully switched off yet, so it's easy to be woken during this stage. If nothing disturbs you, though, you'll slip into stage 2 fairly quickly.

Stage 2: Settling In

Here, your body starts to properly unwind. Your temperature drops, your muscles loosen, and both your heart rate and breathing slow down. This stage tends to make up a large chunk of your total sleep time, as your body prepares for deeper rest ahead.

Stage 3: Deep, Restorative Sleep

This is where the real repair work happens. Often called deep sleep, this stage allows your body to recover and grow, supporting everything from muscle repair to a healthy immune system. You'll spend more time here during the first half of the night, which is one reason those early hours of sleep are so valuable.

Stage 4: REM Sleep

So, what is REM phase of sleep? REM stands for rapid eye movement, and it's the stage where most dreaming happens. During the rem phase of sleep, brain activity ramps up to levels similar to being awake, while your body becomes temporarily paralysed, aside from your eyes and the muscles that keep you breathing. This stage tends to get longer as the night progresses, which is why your most vivid dreams often happen closer to morning.

Why This All Matters

Each of these stages plays a part in how refreshed you feel the next day. When sleep gets interrupted night after night, whether from stress, an inconsistent routine, or an underlying issue like sleep apnea, it can be harder for your body to move properly through these stages and get the rest it needs.¹

If you often wake up tired despite spending enough time in bed, or you suspect something might be disrupting your sleep, it's worth having a chat with your doctor. They can help identify what's going on and guide you towards the kind of sleep that actually leaves you feeling restored.

How Sove CPAP Clinic Can Help

Founded in 2008, Sove CPAP Clinic has grown to become a leading provider of respiratory and sleep services and products in Australia, with over 90 clinics nationwide. Our comprehensive clinical team includes Respiratory & Sleep Specialists, Sleep Technologists, and Treatment Consultants, ensuring that you receive comprehensive and personalised care. All medical procedures, including sleep studies and lung function testing, are bulk billed to all Australians, with minimal wait time.

If you would like to speak to a Respiratory & Sleep Physician, book a bulk-billed sleep study, or seek advice for your sleep apnea, you can reach us at 1300 76 29 39 or info@thecpapclinic.com.au.

References

Suni, Eric. “Stages of Sleep: What Happens in a Sleep Cycle.” Sleep Foundation, Sleep Foundation, 8 Dec. 2023, https://www.sleepfoundation.org/stages-of-sleep. Accessed 29 July 2026.