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Sleep Stages

by Carlo Raj, MD
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      Slides 12 Sleep Neuropathology II.pdf
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    00:01 Hi there! Let’s do sleep.

    00:05 The stages of sleep are defined by the following EEG characteristics, electroencephalogram.

    00:13 Defined as REM versus non-REM and I’ll give you the details as to what exactly that encompasses.

    00:20 Typically, cycle in an orderly fashion over a 90-minute period.

    00:25 Four to six cycles per night in young adults.

    00:29 And REM density decreases as we age, unfortunately.

    00:34 Stage 2 density increases to replace the REM as we age.

    00:40 Let’s take a look at all of this in greater depth.

    00:44 Here, we’ll take a look at non-REM cycle sleeps and their respective stages.

    00:49 Stage 1, loss of posterior alpha rhythm on EEG, typically a brief transition stage.

    00:56 So stage 1, brief.

    00:59 Stage 2: You have sleep spindles and K-complexes on EEG.

    01:06 Make up the majority of your sleep in adults, stage 2.

    01:10 And as I was telling you earlier, remember that REM starts diminishing as we get older, replaced usually by stage 2 more so.

    01:17 K-complexes.

    01:19 Stage 3 will be 20 to 50% of EEG and delta activity.

    01:25 And what that means to you on your EEG is 4 hertz or less.

    01:30 And then stage 4, greater than 50% of EEG would be then delta.

    01:37 Remember, all characterized by reduced but present muscle tone and regular, slow respirations.

    01:45 In fact, when we breathe at night or, excuse me, when we breathe when we sleep, because of the lower respiratory rate, you should remember that there is a possibility that respiratory acidosis is a common and normal occurrence.

    02:02 REM sleep is what’s next.

    02:05 The EEG very much looks similar to that of wakefulness.

    02:10 Rapid eye movement is what REM stands for, horizontal in fashion.

    02:17 Irregular respirations, loss of skeletal muscle tone, except for the eyes and larynx.

    02:24 It has to, so you can breathe and so that you can have the rapid eye horizontal movements.

    02:30 Vivid dreams.


    About the Lecture

    The lecture Sleep Stages by Carlo Raj, MD is from the course Sleep. It contains the following chapters:

    • Sleep
    • Non-REM Sleep
    • REM-Sleep

    Included Quiz Questions

    1. Stage 2
    2. Stage 1
    3. Stage 3
    4. Stage 4
    5. Non REM sleep
    1. Stage 2
    2. Stage 1
    3. Stage 3
    4. Stage 4
    5. REM sleep
    1. REM sleep
    2. Stage 1 of non-REM sleep
    3. Stage 2 of non-REM sleep
    4. Stage 3 of non-REM sleep
    5. Stage 4 of non-REM sleep

    Author of lecture Sleep Stages

     Carlo Raj, MD

    Carlo Raj, MD


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