Hi everyone is some info about the stages we go through during a sleep period...hope you to enjoy it...some facts about sleeping... Complex changes take place in the brain during sleep. It is far from a simple reduction in body process activity. Sleep provides balance in life, being part of a circadian rhythm.Although its process is still not fully understood, the activity of the brain during sleep has been extensively scrutinised and gives an indication of what is happening.Healthy sleep and circadian rhythmsHealthy sleep is considered to be the quantity and quality required to maintain optimal alertness during waking hours. The core time required is 2-5 hours.Over the period of 24 hours, we are synchronised to sleep at night and be awake during the day. This sleep-wake balance is a prime example of a circadian rhythm, our internal time-keeping system. Circadian rhythms are biological cycles within the body that are regulated by hormones.The hormone used in the sleep-wake cycle is melatonin which is secreted by the pineal gland in the brain, known as the third eye due to its ability to react to dark and light.Melatonin levels are at their highest at night as darkness stimulates production in the body. Any exposure to light during the night reduces melatonin production by up to half.REM and non-REM sleepMost people will have heard of REM sleep, the Rapid Eye Movement stage, which can represent one quarter of total sleep time. This is the period when dreams become vivid. Non-REM sleep on the other hand is a deep progressive sleep.We switch between REM and non-REM sleep involuntarily throughout the night. This cycle is more complicated than first appears, with changes in brain activity and body functioning.Stages of sleepThe free falling interim between consciousness and sleep, as we lose sense of our surroundings, lasts about 5-15 minutes. This is the first of five stages. These go in cycles throughout the night, each lasting around 90 minutes.Each stage is characterised by different brain wave patterns which may be measured by an electroencephalogram (EEG).So what exactly is happening?

Non-REM sleep (stages 1-4):The body's metabolism slows down; the brain is least active, blood pressure, heart rate and breathing are lower than during wakefulness. Hormones are secreted, including growth hormone which means that new proteins can go to work on renewal where required e.g. bone and skin. Some digestion takes place.REM (stage 5):The purpose of this stage is less certain. The brain is active, heartbeat and breathing are faster, and voluntary muscles are unable to move. There is a theory that psychological recuperation is occurring during REM sleep, the working out of emotional issues. Alternatively, the brain is sorting images of information that has been gathered throughout the day, filing some into long-term memory and discarding the rest.Stage 1 - the interim between consciousness and sleep (lasts about 5-15 mins)Stage 2 - lose awareness of surroundings, heart rate slows, brain doing less complicated tasks (15 mins)Stages 3/4 - body makes repairs needed, deep non-REM sleep (delta stage). Body temperature and blood pressure decreaseStage 5 - REM - occurs about 90 mins after first feeling sleepy - increase in the contraction of eye muscles, eyes move, mind is active, and heart rate quickens. Breathing, blood pressure, and temperature all increase irregularly. It is during this stage that you wake, sometimes remembering a dream, though dreams are not restricted to this stage.article at here

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