The 5 stages of sleep

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The Five Stages Of Sleep Stage one: when you close your eyes, your body temperature drops and brainwaves become slower. You start to nod off, falling into a light sleep when stress hormones start to drop. Stage two: you've lost consciousness, your digestion slows down and functions like hearing are put on standby. Stage three: the first phase of deep sleep, which usually occurs within 15 minutes of falling asleep. Your muscles relax, your blood pressure and heart rate fall and your brain produces slow waves. Stage four: the deepest sleep of all, which lasts for about two to three hours. These four levels of sleep may play a vital role in energy conservation, growth, tissue repair and information processing. Growth hormone, for instance, is produced during stages three and four. Stage five: our dream sleep, characterised by rapid eye movements (REM), much brain activity and rising blood pressure. Adults average two to three hours of REM sleep a night, mostly towards morning. REM sleep is also vital to our well-being, probably because dreams are a spring cleaning for the mind. It is also known that we have a natural sleep rhythm of around 25 hours, which is brought into line with the 24 hour day by the effects of light. Light falling on the retina stimulates the production of melatonin, which keeps our body clock in time. We also have two periods of sleep-readiness - between 2pm and 6pm and 2am and 6am. Sleep patterns do, however, change as we age. As we get older we get less of stages three and four sleep. After the age of 60, we get very little deep sleep, possibly because we do not need it. Older people tend to sleep and to wake earlier, and to get more broken sleep, often because of the vital trip to the loo, or because of other health problems, such as arthritic pain. REM sleep stays constant through adult

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