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Stages Of Sleep | An Understanding Of Sleep Cycles

Light sleep, deep sleep and REM sleep explained

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Stages of sleep

To accompany the article, Understanding The Basics Of Sleep, this guide will help you appreciate the stages of sleep in more detail.

Stage 1 – Nodding off

Stage 1 is where you sleep most lightly.

It is the transitional phase between consciousness and sleep.

In other words, it’s the “drifting off” phase.

It also describes the period when your drowsiness does eventually turn into a light sleep.

Sometimes people wake from this stage due to experiencing sudden muscle contractions and/or a sensation of falling. This is natural.

You’ve all seen the train commuter nodding-off after a busy day at work, waking him or herself up with a head drop – and if you laughed – shame on you!

Stage 2 – Light sleep

Stage 2 is where your brain waves become slower, heart rate falls, body temperature reduces and eye movement stops.

During stage 2, brain signals sometimes flutter with voltage.

These flutters are referred to as “K-Complexes” (a slow wave of high and low activity) and “Sleep spindles” (a rapid flutter of high and low signals).

K-Complex and sleep spindles

Such activity is reported to occur spontaneously and also in reaction to internal and external stimuli such as breathing interruptions, sounds and touches of the skin.

Sleep spindles are reported to be extremely important in memory consolidation and learning new skills.

Stages 3 and 4 – Deep sleep

When you enter into stage 3, you enter into deep sleep.

Slower brain waves called “Delta” waves become more prevalent but are still interspersed with smaller, faster waves.

Click “Read Here” for a further understanding of delta waves, brain activity and how they influence your state.


Stage 4 is very similar to, and often grouped together with, stage 3, due to the prevalence of Delta waves.

This is when you are hardest to wake (think sleeping beauty without the magic!).

If you are woken in these stages you tend to feel groggy and disoriented.

When entering into stages 4 and 5, your blood pressure tends to drop further, your breathing becomes deeper, slower and more rhythmic, and your body and eyes become motionless.

Although this is the norm, it is not always the case.

Some individuals experience behaviours known as parasomnias which include nightmares, bed-wetting and sleepwalking. Such behaviours tend to occur during transitions between non-REM and REM sleep…

Stage 5 – REM Sleep

Stage 5 is the REM (Rapid Eye Movement) stage.

Researchers often split categories of sleep into REM and NREM (non-REM).

All other stages apart from stage 5 are considered to be stages of NREM sleep.

So what is REM sleep?

REM sleep is where your eyes move rapidly and randomly below your eyelids, and your brain becomes surprisingly active.

Your brain’s oxygen consumption (reflecting energy needed for brain activity) is often higher than when you’re awake; although, interestingly, muscles become completely paralysed and unresponsive (atonia).

Atonia (the relaxation or paralysation of skeletal muscles) occurs because brain impulses, that are responsible for muscle contractions (apart from those controlling eye movements and other essential bodily functions), are completely suppressed.

Breathing becomes faster and more irregular when compared with non-REM sleep, and your blood pressure and heart rate rises to near waking levels.

REM sleep is this strange period where your brain is extremely active but the majority of your body is completely paralysed.

As you may have guessed, this is the period where most of your dreams are created, certainly the most memorable and vivid dreams.

This is the stage mentioned in The Mental Benefits Of Sleep, where you become most creative.

Understanding more about sleep

So there you have it!

Now you understand the stages of sleep I implore you to use our other sleep articles to benefit your health and your life:

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