What do you Know about Sleep?


Main health effects of sleep deprivation (See ...
Image via Wikipedia, maybe you need to

If you are not getting enough sleep, maybe you need to know more about it. It could save you from job loss, family break-ups and simply from being tired all of the time. The following information is for your general use, if you are suffering from any of the symptoms indicated you should contact your Physician.

During sleep, we usually pass through five phases of sleep: stages 1, 2, 3,  4, and REM (rapid eye movement) sleep. These stages progress in a cycle from  stage 1 to REM sleep, then the cycle  starts over again with stage 1. We spend almost 50 percent of our total sleep  time in stage 2 sleep, about 20 percent in REM sleep, and the remaining 30  percent in the other stages. Infants, by contrast, spend about half of their  sleep time in REM sleep.

During stage 1, which is light sleep, we drift in and out of sleep and can be  awakened easily. Our eyes move very slowly and muscle activity slows. People  awakened from stage 1 sleep often remember fragmented visual images. Many also  experience sudden muscle contractions called hypnic myoclonia, often preceded by  a sensation of starting to fall. These sudden movements are similar to the  “jump” we make when startled. When we enter stage 2 sleep, our eye movements  stop and our brain waves (fluctuations of electrical activity that can be  measured by electrodes) become slower, with occasional bursts of rapid waves  called sleep spindles. In stage 3, extremely slow brain waves called delta waves  begin to appear, interspersed with smaller, faster waves. By stage 4, the brain  produces delta waves almost exclusively. It is very difficult to wake someone  during stages 3 and 4, which together are called deep sleep. There is no eye  movement or muscle activity. People awakened during deep sleep do not adjust immediately and often feel groggy and disoriented for several minutes after they  wake up. Some children experience bedwetting,  night terrors, or sleepwalking during  deep sleep.

When we switch into REM sleep, our breathing becomes more rapid, irregular,  and shallow, our eyes jerk rapidly in various directions, and our limb muscles  become temporarily paralyzed. Our heart rate  increases, our blood pressure rises, and males develop penile erections. When  people awaken during REM sleep, they often describe bizarre and illogical  tales-dreams.

The first REM sleep period usually occurs about 70 to 90 minutes after we  fall asleep. A complete sleep cycle takes 90 to 110 minutes on average. The  first sleep cycles each night contain relatively short REM periods and long  periods of deep sleep. As the night progresses, REM sleep periods increase in  length while deep sleep decreases. By morning, people spend nearly all their  sleep time in stages 1, 2, and REM.

People awakened after sleeping more than a few minutes are usually unable to  recall the last few minutes before they fell asleep. This sleep-related form of amnesia is the reason people often forget telephone calls or conversations  they’ve had in the middle of the night. It also explains why we often do not  remember our alarms ringing in the morning if we go right back to sleep after  turning them off.

Since sleep and wakefulness are influenced by different neurotransmitter signals in the brain, foods and medicines that change the  balance of these signals affect whether we feel alert or drowsy and how well we  sleep. Caffeinated drinks such as coffee and drugs such as diet pills and  decongestants stimulate some parts of the brain and can cause insomnia, or an inability to sleep. Many antidepressants suppress REM sleep.  Heavy smokers often sleep very lightly and have reduced amounts of REM sleep.  They also tend to wake up after 3 or 4 hours of sleep due to nicotine withdrawal. Many people who suffer from insomnia try to solve the  problem with alcohol-the so-called nightcap. While alcohol does help people fall into light sleep, it also robs them of REM and  the deeper, more restorative stages of sleep. Instead, it keeps them in the  lighter stages of sleep, from which they can be awakened easily.

People lose some of the ability to regulate their body temperature during  REM, so abnormally hot or cold temperatures in the environment can disrupt this  stage of sleep. If our REM sleep is disrupted one night, our bodies don’t follow  the normal sleep cycle progression the next time we doze off. Instead, we often  slip directly into REM sleep and go through extended periods of REM until we  “catch up” on this stage of sleep.

People who are under anesthesia or in a coma are often said to be asleep. However, people in these conditions cannot  be awakened and do not produce the complex, active brain wave patterns seen in  normal sleep. Instead, their brain waves are very slow and weak, sometimes all  but undetectable.

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By hotdogfish Posted in Living