To an observer of a sleeping person, sleep may seem like a very uncomplicated function of the body. Seemingly at peace, the body remains mostly still and little emotion is being conveyed by the person asleep. This would give somebody the idea that sleep is the ultimate, natural state of rest... This, however, is not totally true. In recent years, much has been uncovered about the truth of sleep. The brain goes through a series of stages that are actually fairly amazing if you spend the time to learn more about them.
There are 5 different stages of rest that the brain typically goes through while asleep. In stage 1 your brain powers down by 50%, producing theta waves which typically occur four to seven times per second. This stage of rest is very calm, and the sleeper may not even be totally sure whether or not they are awake. During stage 2 your brain powers down even more. Your heart rate slows and your muscles become relaxed, this is the stage we associate most often with being asleep as you spend up to 65% of your time in the second stage. In stages 3 and 4, your brain only produces waves once or twice a second. Stage 5 of sleep (otherwise known as REM Sleep) is where your brain kicks into high gear and the any typical rumors of your brain resting while asleep are debunked. During this stage, your brain produces high-frequency, low-amplitude waves that are very similar to being awake. A quickening heart rate, increased blood pressure, and irregular breathing are all typical of REM sleep. We typically cycle through these stages of sleep 5 to 6 times per night! Along with theses 5 stages are a variety of sleep disorders and other unconscious behaviors that can make some people even more active while being asleep.
It is interesting how our brains can be so active throughout the night without us having to think at all about what we are going through. These unconscious processes can be so complicated that is is a wonder how we can wake up feeling so well rested in the morning!