The Four Sleep Stages

Understanding what happens when we sleep 

Scientists have identified four different sleep stages which reoccur during the night. Their frequency and duration will vary during the night and each one has a distinct purpose. A sleep cycle is composed of multiple sleep stages. Typically each sleep cycle will take between 90 minutes and 110 minutes and then the will repeat 3 to 6 times per night. The pattern and length of the cycles will determine the overall quality of our night’s sleep.

 How do we distinguish between the sleep stages?

The most common way is through measuring the brain waves. The activity within your brain is unique for each sleep stage. However there are also physical symptoms associated with each stage.

Why do we have sleep stages?

There is much which we don’t know about sleep but we can say that each stage benefits us in different ways.Whether it is physical restoration or the processing of our emotional feelings they each serve a purpose.

How will knowing about sleep stages actually help me to sleep?

The more we understand about sleep the better chance we have of making the most of this precious resource. Think of this as being similar to a biofeedback mechanism.

What are the four sleep stages?

Stage One – Light sleep. This is the type of sleep when you are drifting in and out and sometimes your legs will twitch or you get a sensation of falling. Stage one sleep is often associated with power napping.

Stage Two – Deep sleep. This accounts for about half of your sleep. Your body is now slowing down, your eyes are still and your brainwaves are also slower. Interestingly you can also get brief bursts of brain activity called sleep spindles. During deep sleep it can be very difficult to wake up. It is during deep sleep that people will sometimes sleep talk or sleep walk. Previously this stage was split into two with the first stage being characterised by spikes in the brain activity.

Stage Three – REM sleep. This happens when you are dreaming and it is characterised by rapid eye movements or REM. Your breathing will be faster, shallow and irregular. As your eyes start to move so your muscles will be become fixed and immobile. The REM cycle becomes more prominent during the later part of the night (and the deep sleep stages reduce correspondingly).It is during REM sleep that we will dream.

Stage Four – Wakefulness. It is actually normal to have brief periods of wakefulness during the night. The whole night’s sleep is not just one continuous span where you go deeper and deeper into sleep.It is in fact broken up into many smaller cycles.

Conclusion

We have seen how there is a structure to sleep and an order as to when these stages happen. We know that the typical sleep cycle runs for 90 minutes each time and that each part brings its own benefits.

Knowledge of sleep stages and cycles is key to understanding how we can improve our sleep.