Though we might think that our bodies simply shut down and totally relax during sleep, in fact many parts of the body remain surprisingly active. This is particularly true of the brain which sends out a constant stream of signs controlling what’s called our sleep cycle.
There are five stages to a normal sleep cycle and, on a fantastic night’s sleep, you may experience all five of them several times in series. The five phases of sleep have been broadly divided in two classes. The first class, which comprises the first four stages, is called non-rapid eye movement or NREM sleep, while the second group, which comprises only a single stage, is referred to as rapid eye movement or REM sleep.
The main difference between NREM and REM sleep is seen concerning the brains action. Additionally, REM sleep can be characterized by intermittent but rapid breathing and pulse, a rise in blood pressure and almost no muscle activity.
Throughout a normal night’s sleep that you pass through the many phases of sleep several times, but have a tendency to spend on the first third of sleep at the NREM stages and the last third of sleep at a REM stage.
Period 1 is the point where you fall asleep and finds you feeling tired and drifting in and out of sleep. Eye movements begin to slow during stage 1 and you begin to lose control over your muscles. It’s also quite common in this stage to experience abrupt contraction and jerking of the muscles.
About half of sleep is stage 2 sleep during that your brain activity and heart rate slows, your temperature drops and eye movement is reduced to virtually none in any way, although there can be occasional brief bursts of eye motion.
Both phases 4 and 3 are very similar and, together, are known as sleep. Brain waves through both of these phases are very slow and there is no movement in either the eyes or the muscles.
REM sleep is interspersed through the different phases of sleep, which don’t necessarily follow a strict numerical sequence, and, in total, represents about a quarter of the period spent in sleep. The first period of REM sleep for example follows stage 1 and continues for only about ten minutes, while the last period of REM sleep, where you normally wake up, lasts about one hour.
This repetition of these sleep phases increases the sleep cycles and a regular night’s sleep consists of many sleep cycles. As these cycles continue throughout sleep, REM sleep is also seen to grow. Although it is difficult to restrain our sleeping cycles, there is a fantastic deal that we can do to prevent these cycles from getting disrupted and thus to guarantee sound sleep and, where required, to help to cure insomnia.