Sleep Stages

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.

01:31 Remember, all characterized by reduced but present muscle tone and regular, slow respirations.

01:39 REM sleep is what’s next.

01:43 The EEG very much looks similar to that of wakefulness.

01:48 Rapid eye movement is what REM stands for, horizontal in fashion.

01:54 Irregular respirations, loss of skeletal muscle tone, except for the eyes and larynx.

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

02:07 Vivid dreams.