Sleep is one of the activities humans cannot do without. It is during sleep that our body resets and prepares for another day. It is safe to say sleep may even more important than food (water and solid foods). This is because one can go survive for 8 to 21 days without food and water and up to two months if there’s access to an adequate water intake. But a person’s body will begin to shut down if he misses more than 11 days of sleep. Sleep is undoubtedly important. In this article, we will look at the processes that happen during sleep.
Sleep is a condition of the body and mind that typically recurs for several hours every night, in which the nervous system is relatively inactive, the eyes closed, the postural muscles relaxed, and consciousness practically suspended.
It is known that, when we sleep, our body becomes paralyzed but that is not entirely true. This is because at a certain stage during sleep, the eyes continue to blink and move as if they were awake- the only difference is that it does this whilst being closed.
Because of this reason, sleep has been divided into two main stages:
· Non-rapid eye movement (NREM): stage 1-3
· Rapid eye movement: stage 4
The stages are categorized based on the electrical activity in the brain which is measured by an instrument called Electroencephalogram(EEG). There are different brain activities during each stage.
The truth is that humans don’t sleep continuously throughout sleep. They go through several stages-stage1 to stage 4. These cycles repeat every 90-110 mins till a person wakes up.
Human beings will begin to sleep from stage 1-stage 4, then repeat the process all over again until they wake up. However, the duration of the sleep stages will change in different cycles.
Non-rapid eye movement (NREM)
This involves the light, restful and deep sleep categorized by stage1, stage 2 and stage 3 respectively. During this stage, the body becomes paralyzed.
Rapid eye movement
This is the stage where humans have dreams plus restoration of the body and mind takes place during this stage. Unlike the others, the body becomes paralyzed except for the eyes and muscles that control breathing.
Stages in sleep
This is the light stage of sleep. It is the transition from being awake to sleeping. If a person is awoken at this stage, they may claim they were not sleeping. It is usually termed the dozing off stage. It lasts between 1-5 minutes. However, as the night progresses, and the cycle begins all over again, this may become even shorter.
This stage is also a light stage but it is characterized by a slowing down of brain waves. Sleeping during this period is pretty comfortable. The temperature of the individual drops, the muscles begin to relax, the breathing and heart rate slows down. This stage will last between 10-25 minutes. Also, the time may become longer as the cycle repeats itself. It is known that a person spends about half of their sleep time during this phase.
This is the stage when a person is deep into sleep. If you wake a person up when he is in this stage, he will sound very confused. In fact, it is even difficult to wake someone up from this stage. The temperature, heart rate, breathing rate slows down even further. The muscles also relax.
Experts believe that this stage is critical to restorative sleep, allowing for bodily recovery and growth. It may also bolster the immune system and other key bodily processes. Even though brain activity is reduced, there is evidence that deep sleep contributes to insightful thinking, creativity and memory.
Also, this is the stage when people can wet their beds, sleepwalk or night terrors are experienced. It happens when they stay in this stage for too long. All these have causes and are abnormal.
Stage 4-Rapid eye movement (REM)
As mentioned earlier, this stage is characterized by the movement of the eyes during sleep. The eyes may move side to side whilst still closed and breathing patterns become irregular. This is because the eyes and the muscles that control breathing become activated.
REM sleep is important because brain activities almost look almost the same when you are awake. The REM stage is important because it is important for memory, creativity and learning. The body produces serotonin in increasing amounts during this stage. Serotonin affects mood and may help get rid off of depression and anxiety. This explains why you feel better emotionally after sleeping.
At this stage, a person can dream and remember the dream clearly. Most dreams occur in this stage. Dreams may occur in the other stages, but they are less common and intense during stages 1-3 unlike stage 4.
An individual completing the REM stage (stage 4) may either wake up briefly and go back to stage 1 to continue the cycle.
REM sleep is usually shorter in the first cycle of sleep, but it may increase progressively to an hour during the next cycles. The stages (1-4) will repeat233 about 4-5 times each night, with each cycle lasting between 90-110 minutes.
These stages in sleep are important because; the body rests and recuperates, long-term memories are formed, the immune system is boosted, the creativity and learning ability of the individual is enhanced and many more. The stages will repeat about 4-5 times each night, with each cycle lasting between 90-110 minutes.
Why we dream.
Dreams are hallucinations of one's thoughts whilst asleep. Most dreams make little or no sense. This is because the part of the brain(amygdala) that is most active during this period affects emotions instead of logic. When one is awake, our thoughts make sense because the logical part of the brain is active (frontal lobe).
One study suggests that dreams stem more from your imagination (the memories, abstract thoughts and wishes pumped up from deep within your brain) than from perception (the vivid sensory experiences you collect in your forebrain).
Nightmares are dreams that are frightening or upsetting usually from stress, anxiety or a response to some medication. However, if they occur often, it might be a sign of a sleep disorder.
Dreams are difficult to remember because the chemical associated with memory-norepinephrine is at its lowest during REM sleep. Also, if a person does not wake up during or after the REM stage, that individual will forget his dream.
Dreams are important and even though science continues to explore the reason why we dream, there are still gaps that need to be filled.
- Sleep foundation. Stages of sleep. Retrieved from https://www.sleepfoundation.org/how-sleep-works/stages-of-sleep
- Healthline. Why we dream. Retrieved from https://www.healthline.com/health/why-do-we-dream
3. Dreaming and the brain: from phenomenology to neurophysiology. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2814941/ .
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