Importance of Sleep-Sleep stages

Importance of Sleep-Sleep stages

We often forget the importance of sleep for our well-being. This blog will reflect on the different stages of sleep. The second blog will reflect of sleep deprivation and the benefits of sleep.

There are two distinct classes of sleep; 1) Slow-wave-sleep (SWS), Sleep divided into stages 1-through 4, that is defined by the presence of slow-wave EEG activity. 2) Rapid-Eye movement sleep  (REM), also called paradoxical sleep. A stage of sleep characterised by small-amplititude, fast electroencephalography (EEG) waves, no postural tension, and rapid eye movements (Aserinsky and Kreitman, 1953).

Sleep is measured through EGG, below will be a mini description of the waves we experience when we sleep, that in turn help us understand the stages we are in.

Stage one of sleep: this is the initial stage of slow wave sleep , which is characterised by small amplitude EEG waves if irregular frequency, slow heart rate, and reduced muscle tension.

Stage two sleep: A stage of slow wave sleep that is defined by bursts of regular 14-to 18 Hz waves called sleep spindles and K complexes.

Stage three of sleep: A stage of slow-waves sleep that is defined by the spindles seen in stage 2 sleep, mixed with larger-amplitude slow waves.

Stage four sleep: A stage of slow-wave sleep that is defined by the presence of delta waves at least half the time.

From stage four we encounter REM sleep. REM sleep is where we encounter vivid dreams that are well organised, this is our dreaming state. But not all dreams are encountered in this stage, research has shown nightmares or night terrors happen in REM sleep. Why is that you may wonder? Research by Cartwright (1979) is that REM sleep is usually characterised by visual imagery, some dreamers remember smells, sounds and acts. While, in non-REM sleep the brain dreams of thinking issues, such as thinking of a problem.

The next blog on sleep will describe the impact of sleep deprivation. Hope this helps to bring you some insight in the stages of sleep and when we dream.

By Dr Farah Nadeem

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