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Sleep Stages

by Carlo Raj, MD
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      Slides 12 Sleep Neuropathology II.pdf
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    Hi there! Let’s do sleep. The stages of sleep are defined by the following EEG characteristics, electroencephalogram. Defined as REM versus non-REM and I’ll give you the details as to what exactly that encompasses. Typically, cycle in an orderly fashion over a 90-minute period. Four to six cycles per night in young adults. And REM density decreases as we age, unfortunately. Stage 2 density increases to replace the REM as we age. Let’s take a look at all of this in greater depth. Here, we’ll take a look at non-REM cycle sleeps and their respective stages. Stage 1, loss of posterior alpha rhythm on EEG, typically a brief transition stage. So stage 1, brief. Stage 2: You have sleep spindles and K-complexes on EEG. Make up the majority of your sleep in adults, stage 2. And as I was telling you earlier, remember that REM starts diminishing as we get older, replaced usually by stage 2 more so. K-complexes. Stage 3 will be 20 to 50% of EEG and delta activity. And what that means to you on your EEG is 4 hertz or less. And then stage 4, greater than 50% of EEG would be then delta. Remember, all characterized by reduced but present muscle tone and regular, slow respirations. 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. REM sleep is what’s next. The EEG very much looks similar to that of wakefulness. Rapid eye movement is what REM stands for, horizontal in fashion. Irregular respirations, loss of skeletal muscle tone, except for the eyes and larynx. It has to, so you can breathe and so that you...

    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

    Author of lecture Sleep Stages

     Carlo Raj, MD

    Carlo Raj, MD


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