1-3a Reading - Sleep Cycles

The Cycles of Sleep

When someone falls asleep, they enter into a state of unconsciousness that results in extreme physiological changes in how both the mind and body function. Scientists continue to research the properties of sleep, especially the stages that people enter when sleep occurs. Regardless of age or the total amount of time needed for healthy sleep, people sleep in four distinct stages which are repeated throughout the night that make up their sleep cycle.

The first stage of sleep occurs when people are just beginning to fall asleep and at this point, people are in a state somewhere between being asleep and awake. At this time, the muscles of the body are still active and the eyes may continue to open and close slightly. People may experience periods of dreaminess at this time, much like day dreaming during the day, but it is not real dreaming, which occurs later on. During stage one, which lasts around 5 to 10 minutes, it is fairly easy to awaken the sleeper; however, at stage two it becomes gradually harder to do so as this is the first stage of true sleep (HHS, 2005). Large physiological changes occur over the 10 to 25 minutes of this stage such as the stopping of eye movement, slowing of heart as well as breathing rate, and decreasing of body temperature.

Following the relatively lighter stage one and two sleep, sleepers enter into the deepest part of the sleep cycle in the third stage when they become much less responsive to any outside stimuli, which evokes little to no reaction. Interestingly, it is during this stage that people may experience a great deal of movement in the form of sleepwalking, a condition knows as somnambulism. The body repairs itself over the 30 minutes of this stage and stores energy for the coming day, so it is crucial for maintaining health, stimulating growth, repairing tissues, and boosting the immune system (NINDS, 2014). Being awoken during this stage results in unpleasant feelings of grogginess and disorientation which can last for several minutes.

The final stage of sleep, known as Rapid Eye Movement or REM sleep, is where dreaming occurs. Surprisingly, although the muscles are paralyzed during this stage, it is in fact one of the lighter sleeping periods in the night and is marked by a large increase in brain activity. Just as stage three sleep helps renew the body physically, REM sleep seems to help the mind by consolidating and processing information taken in and learned during the day as well as strengthening neural connections in the brain itself (NINDS, 2014). The whole cycle from Stage 1 through REM sleep occurs repeatedly throughout the night about every 60 to 90 minutes or so.

All people need sleep and are healthier when they get the sleep they need. When a good nights sleep is allowed to follow its natural path through all four stages of the sleep cycle, from Stage one to REM sleep, the true benefits of sleep are realized. As more research is done, surely more secrets about the purpose of sleep will be revealed.

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