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Saturday, March 23, 2024

The Five Stages of Sleep

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When we think of sleep, we think of giving the body and
mind a few hours a day to rest and rejuvenate. We yearn for more hours of sleep because it gives us the energy that we need to perform our daily activities. This is our perception of sleep- temporarily turning off of our physical and mental faculties at night so we can have an energy-filled day the next morning.
Several interesting findings were established since scientists have found ways to measure brain activity. One of them is the discovery that sleep consists of five different stages. By using an electroencephalograph, doctors were able to identify that sleep is divided into five different stages, each of which manifest a distinct set of qualities. Further studies on human brain activity revealed that sleep advances through stages as manifested by different sets of brain wave patterns.

Stage 1

It should be noted that humans display two general types of brain wave activity namely the Beta Wave and the Alpha Wave. The former is most often detected when we are wide awake, while the latter is present during the state of sleep.

Beta Waves are low amplitude, high-frequency waves that lack synchrony compared to other types of brain wave patterns. The desynchronous nature of Beta Waves is made apparent by the various mental tasks that humans perform when wide awake.
On the other hand, Alpha Waves feature synchrony as it shows that an individual is in a relaxed and restful state of being. While the frequency of brain wave activity decreases, the amplitude increases at the same time. It should be noted that Alpha Waves are not only seen when a person is in deep slumber. There are
certain activities that can convert Beta Waves into Alpha Waves like meditation and relaxation exercises.

Stage 2

The Theta Waves activity continues through the second stageof sleep. The two defining characteristics observed during Stage 2 is the appearance of K complexes and sleep spindles. There is a sudden increase in both the frequency and amplitude of brain wave activity in Stage 2. It is also during this stage that core body temperature and heart rate begin to gradually decrease. It may not even feel like you are already sleeping during the first two stages of sleep as brain wave activity still hasn’t shifted completely from Beta to Alpha Wave activity.

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Stage 3 and Stage 4

Stages 3 and 4 of sleep are characterized by the appearance of Delta Waves. It is during the third stage that we are most likely to transition from light sleep to deep sleep. Delta Waves are known to be highest in amplitude and lowest infrequency. There are no distinguishing qualities that clearly separate the third and fourth stage of sleep, except that there are more than 50% of Delta Waves during Stage 4 sleep. We are most likely to feel disoriented and sleepy when awakened during these sleep stages. In addition, sleep disorders namely sleep walking, sleep talking, and bed wetting mostly occur during Stage 3 or Stage 4 ofsleep.

Stage 5 or REM Sleep

As the name implies, REM sleep is characterized by rapid eye movement and temporary paralysis of skeletal muscles. The brain wave patterns during Stage 5 are a combination of desynchornous Alpha and Beta Waves. It is during the fifth stage of sleep when we are most likely dreaming. Paradoxical sleep is a term associated with Stage 5 of sleep as brain activity and other bodily functions increase while body movement is in a more relaxed and restful state.

The Stage 5 of sleep only last for 15 minutes during the first cycle of sleep. Once REM sleep ends, it goes back to Stage 2 and so forth. During the second and succeeding cycles, Stages 2 to 4 become shorter while REM sleep progressively becomes longer in duration.

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