One interesting aspect of this chapter is the sleepwalking section. Sleepwalking affects 15 to 30 percent of children, and only 4 to 5 percent of adults. Sleepwalking usually doesn't entail lots of activity, however people have been known to drive cars, partake in sexual intercourse, even commit murder. For most people however, sleepwalking is harmless, and sleepwalkers can be woken up safely, contrary to popular belief.
There are four stages of sleep, stage 1 is a light stage of sleep, which tends to last about 10 minutes. In this stage our brain activity decreases by 50 percent we become relaxed and begin to drift into a deeper sleep.
In stage 2 our brains slow down even more. As out brains activity decelerates, our hearts slow down, and our body temperature decreases, our muscles relax, and our eyes stop moving. we spend about 65 percent of our sleep in stage 2.
In stage 3 and 4 we progress to a deeper slow- wave sleep. If you were to look at an EEG you would see that delta brain waves appear 20 to 50 percent of the time. These deeper cycles of sleep are important as they allow us to feel well rested the next day. Children spend about 40 percent of their sleep time in deep sleep,as opposed to adults who spend only about a quarter of their sleep time in deep sleep.
we spend about 15 to 30 min in stage 5, before returning to stage 2. We return to stage 2 before our brains shift dramatically into high gear, which high frequency, low amplitude waves, resembling those of wakefulness. Stage 5 is most commonly known as REM sleep. In REM we have increased heart rates and blood pressure which is accompanied by irregular breathing. After about 20 min of REM we drift back to earlier stages before returning to the deeper levels of sleep.
This chapter held lots of interesting information about sleep disorders and other neat phenomenons, with one of the most interesting being out - of body experiences. Out of body experiences are a sense of your consciousness leaving your body. these are surprisingly common, and about 25 percent experience them. most cases have described it as themselves floating about their bodies, calmly observing themselves from above.