Four Stages of Sleep

" People often joke about sleep being the ultimate luxury; however, sleep is a necessity. Humans need to sleep in order to maintain a healthy mind and body. A friend of mine is having trouble falling asleep at night and if she does fall asleep, she is getting roughly two hours of it. In an attempt to inform my friend of the dangers her sleeping habits might bring, I chose to research the factors that can affect when someone gets tired, the different stages of sleep and sleeping disorders.

There are a few factors that can determine when someone gets tired. Two of which include: an environmental factor and a physiological factor. Daylight savings is a perfect example as to how the environment can affect our sleepiness. Twice a year, we intentionally change the time on our clocks so it matches with the sunrise and the sunset. When we set the clock forward an hour, we feel more tired as a result of lost time. When we set the clock back an hour, we will feel more energized as a result of gained time. A physiological factor that affects when we get tired is age. The older we get, the less amount of time we spend asleep. Newborns spend at least 16 hours of their day sleeping whereas an adult only needs eight hours of sleep to function normally. REM sleep is also affected by age. As age progresses, the amount of time spent in REM sleep is decreased.

There are four different stages of sleep: Stage 1, Stage 2, Stage 3-4 and rapid eye movement, otherwise known as REM. Stage 1 is known for being the lightest stage of sleep. The EEG brain frequency during this stage produces theta waves that are somewhat slower than when the brain is awake. Stage 2 of sleep is typically after Stage 1 and it represents a deeper sleep. The EEG brain frequency during this stage is characterized by sleep spindles and K-complexes. Stage 3-4 of sleep is the deepest of all the stages. The EEG brain frequency in Stage 3-4 produces delta waves. REM, the final stage of sleep, is known for being associated with dreaming. The EEG brain frequency during REM sleep looks very similar to when the brain is awake. During a typical night of sleep, a person experiences four to five cycles of sleep. A sleep cycle is an advancement through the stages of sleep starting with Stage 1 and ending in REM, only to begin again. One cycle can last anywhere from 90 to 120 minutes.

My friend’s EEG shows that the amount of time she is spending in the REM stage is above normal. This is consistent in people with narcolepsy who typically enter REM sleep within 15 minutes of falling asleep. Narcolepsy is a sleep disorder that causes its sufferers to become overwhelmed with drowsiness. Its symptoms include excessive amounts of sleep, hallucinations and even loss of muscle tone which is caused by cataplexy. There are two types of narcolepsy: Type 1 narcolepsy, which is narcolepsy with cataplexy, and Type 2 narcolepsy, which is narcolepsy without cataplexy. Those who are diagnosed a narcoleptic with cataplexy will experience the same symptoms as someone who is just diagnosed a narcoleptic with the exception of sudden losses of muscle tone. "

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