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UNDERSTAND YOUR SLEEP

How Sleep Works: Cycles, Stages & Your Body Clock

Sleep is an active biological process rather than one long, unchanging state. Explore sleep cycles, light and deep sleep, REM, circadian rhythm, dreaming and the signals that help your body move between rest and wakefulness.

Understanding sleep cycles and stages

Sleep Changes Throughout the Night

As you sleep, your brain and body move through repeating stages rather than staying in one level of sleep. Lighter sleep helps you transition into rest, deeper stages are associated with physical restoration, and REM becomes more prominent later in the night.

The balance of those stages changes from cycle to cycle, which is one reason the same number of hours can feel very different depending on how continuous and restorative your sleep has been.

Read about the sleep cycle

What Shapes a Night of Sleep?

Several biological processes work together while you rest:

✓ Repeating cycles of lighter, deeper and REM sleep ✓ Your circadian rhythm and exposure to light ✓ Sleep pressure that builds while you are awake ✓ Natural changes in body temperature overnight ✓ Brief awakenings between cycles ✓ Dreaming and memory processing during sleep ✓ The timing and consistency of your sleep schedule ✓ Age, health, lifestyle and individual sleep need

Understand More About Your Sleep

Explore sleep duration, waking, naps, dreams and unusual sleep experiences in more depth.

When Should You Go to Sleep?Think about sleep need, wake-up time, routine and how your schedule fits your life.→ How Naps Move Through Sleep StagesLearn why nap length affects alertness, deep sleep and sleep inertia.→ Understanding Sleep ParalysisExplore what happens when REM-related muscle atonia overlaps with waking awareness.→ Recognise Sleep DeprivationSleep length is only part of the picture; continuity, timing and quality matter too.→ Why Do I Wake Up Tired After 8 Hours?See why time in bed and restorative sleep are not always the same thing.→ How to Wake Up EasierUnderstand sleep inertia, sleep cycles and why some mornings feel harder than others.→ Is Six Hours of Sleep Enough?Explore sleep need, individual variation and the idea of accumulated sleep debt.→ Recurring Dreams: What They MeanLearn why some dream themes repeat and how recurring dreams fit into the wider picture of sleep.→

Explore Related Sleep Topics

Continue learning across Myza's sleep hubs.

Bedtime RoutinesSleep hygiene, wind-down habits and evening cues.→ Your Bedroom EnvironmentLight, temperature, noise and comfort.→ Mind & RelaxationBreathing, anxiety, journaling and calming habits.→ Sleep Aids & TechnologyTrackers, light therapy and sleep technology.→
Sleep science and dreaming

How Sleep Works FAQs

What are the main stages of sleep?

Sleep is usually described as moving through several non-REM stages followed by REM sleep. These stages repeat in cycles and the balance between them changes across the night.

How long is a sleep cycle?

Around 90 minutes is often used as a rough guide, but cycle length varies between people and also changes across the course of a single night.

What is REM sleep?

REM stands for rapid eye movement sleep. It is a stage associated with vivid dreaming, memory processing and emotional regulation, while the brain remains highly active.

What is deep sleep?

Deep sleep is a slow-wave non-REM stage associated with physical restoration. It is usually more prominent earlier in the night.

What is a circadian rhythm?

Your circadian rhythm is the roughly 24-hour internal timing system that helps regulate sleepiness, alertness, body temperature and other daily biological processes.

Why do I sometimes wake feeling groggy?

Waking from deeper sleep can cause temporary sleep inertia, a period of grogginess or reduced alertness while the brain transitions fully into wakefulness.

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