Sleep it is one of the most desired states of being for many; and the most elusive for even more.
Even though it may appear to be nothing more than an ‘unconscious state’ of being; there are several complex activities occurring while you are sleeping. Within this complexity are the two basic types of sleep that we experience.
Non-REM and REM (rapid eye movement). Non-REM progresses through three stages leading into the fourth and final one which is REM sleep. This occurs in a cyclic manner returning to stage one at the end of REM sleep.
Each stage generally lasts for around 5- 15 minutes with a complete sleep cycle averaging approximately 90-110 minutes. These cycles occur several times during a typical sleep.
There is a direct relationship between adequate sleep and good physical and mental health. Deep sleep is necessary for the regeneration of the nervous system and cell repair. It is when the body can best rebuild tissue, bone and muscle and strengthen the immune system. Long term memory requires both non-REM and REM sleep.
Stage 1 non-REM
The transition from wakefulness into light sleep begins. Brain wave activity slows down along with your heart rate, breathing and eye movements. You may be mildly aware of occasional muscle twitches and can easily be awakened at this time. This phase lasts for around five to ten minutes.
Stage 2 non-REM
Light sleep continues to progress, and fragmented dreams occur. Your breathing changes as the muscles in your upper airways relax making the airways narrower. Body temperature decreases and eye movements stop. You spend more of your repeated sleep cycles in stage 2 sleep than in other sleep stages.
Stage 3 non-REM
This is the deepest and therefore most essential period of sleep to aid rest and recovery. It occurs in longer periods during the first half of the night. Your heartbeat and breathing slow to their lowest levels during this phase. Brain waves become even slower and muscles are extremely relaxed. It may be difficult to awaken someone at this stage of sleep, and they would likely feel confused and disorientated.
REM sleep occurs about 90 minutes after falling asleep. Your eyes move rapidly from side to side behind closed eyelids. Your breathing becomes faster and irregular, and your heart rate and blood pressure increase to near waking levels. Most of your dreaming occurs during REM sleep, although some can also occur in non-REM sleep. Your arm and leg muscles become temporarily paralysed, which prevents you from acting out your dreams. Changing sleep patterns and lower production and secretion of serotonin are likely causes for less time spent in REM sleep as you age.