Stage 2 non-REM sleep

Stage 2 non-REM sleep, also known as N2, is the second stage of non-REM sleep. It comes after the ~ten minutes of sleep onset which marks the transition from wake to sleep. In this stage of sleep, we continue to have slow theta brainwaves, but we also have two different kinds of sudden bursts of activity that characterise this stage of sleep. One of these is sleep spindles, which are sudden bursts of very quick (high frequency) waves, and the other is k-complexes, which are sudden bursts of very large (high amplitude) waves. Dreams in N2 tend to be different to those in REM sleep; generally speaking, N2 dreams are more clearly relatable to waking life, more about waking-life concerns, shorter, less vivid, less bizarre, and more like waking-life thoughts. We also have fewer dreams in non-REM sleep than REM sleep. However, the differences between non-REM and REM dreaming are not completely clear-cut, because in the later part of the night, towards the morning, N2 dreams become much more like REM dreams, to the point that they can become indistinguishable. So the amount of time you’ve been asleep affects your dreams, as well as the stage of sleep you’re in.  To see where in the night this stage of sleep occurs, take a look at a typical hypnogram. The fantastic diagram below from the website HumanPhysiology.Academy illustrates what our brainwaves look like in the different stages of sleep. You can see that sleep spindles are very frequency bursts of activity, while K-complexes are very high amplitude bursts of frequency.

EEGs sleep stages

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