Stage one is a light sleep, one in which you can be very easily awoken, and usually lasts 1-7 minutes. Your breathing and heart rate slow down while your brain produces slower less frequent theta waves. In this stage, it is common to feel sensations such as falling or floating.
Next is stage 2. Here you are clearly asleep and not easily awoken, this lasts around 20 minutes on average. Your breathing and heart rate still decrease as well as muscle tension and body temperature. Your brain continues producing theta waves but also produces sleep spindles, bursts of electrical activity. Study suggests these sleep spindles help process both simple and complex motor skills we have learned.
Stage 3 is the first slow-wave sleep. Your brain begins producing large, slow delta waves.
Once a consistent pattern of delta waves are produce, you have moved into stage 4 sleep. This is a very deep sleep and your body is extremely relaxed. Heart rate, respiration, body temperature, and blood flow to the brain have all decreased. It is here when body maintenance and restoration occur as well as growth hormone being secreted.
After cycling back through stage 2 your body enters REM sleep. this is a very active stage of sleep. Your breathing increases, heart rate becomes irregular, blood flow increases to the genital area, and muscle tone decreases drastically leaving you very relaxed and essentially paralyzed. It is this stage of sleep that dreams occur. Although it is possible to dream in all stages, REM and dreaming are intimately connected and are much more easily recalled when awoken from this stage.
Textbook (What is Psychology?) pages 140-143
Re:
This is a very nice summary of the stages of sleep and how we progress through them. However, you did not use the class videos or any outside resources to add to this. Doing this "extra" will help you get higher grade in future posts.
Be sure to respond to another classmates post as well before the end of Tuesday in this coming week.