Question

Your psychology instructor states that during a night of sleep, a person goes through cycles of light and deep sleep, while also experiencing bodily changes. Using a description of the stages of NREM and REM, describe a night of sleep, including the type of brain waves present and the characteristics of each NREM stage and the characteristics of REM sleep.

Answer 1

A normal sleeping hour is somewhere between 6-8 hours. During these hours, an individual goes through the various stages of sleep. The NREM and REM stages of sleep. 50 years back, we never had the technology to understand the sleep patterns, but today, thanks to the technologies like EEG (electro-encephalo-graph) which has made it possible to record the wave patterns during sleep.

An individual goes through 5 stages of sleep. The first 4 stages is called as the Non-Rapid Eye Movement sleep and the last stage is called as the Rapid Eye Movement sleep. Different wave patterns during sleep say much about the quality and the quantity of the sleep.

Stage 1:

The stage 1 sleep is characterized by the Alpha waves which is faster and shorter waves. This is often called as the light sleep stage. This is where an individual drift into sleep. The individual can be awakened without any difficulties as this stage is still active and people can often remember fragmented visual images. Further, it is at this stage that people experience an Hypnogogic Myoclonia or also called as Hypnogogic Jerks, which is experienced suddenly during sleep. It is preceded by a sudden sensation of falling from a high place. Or feel that someone is calling your name.

The individual then begins to enter Theta, which is still a relatively light period between being awake and asleep. This usually lasts for 5-10 minutes. Research has shown that the average sleeper takes about 7 minutes to fall asleep. One may fall asleep sooner, or take longer. Once this stage is successfully cleared, the individual pass on to the second stage.

Stage 2:

The second stage of sleep lasts about 20 minutes. Our brain begins to produce very short periods of rapid, rhythmic brain wave activity known as Sleep Spindles. Body temperature begins dropping and heart rate starts slowing down.

Stage 3:

The third stage of sleep is the beginning of the Delta sleep or Delta waves, which is characterized by long and slow waves. It is a transitional period between light sleep and very deep sleep state. At this stage the individual will not experience any eye movement or a muscle activity. And it is usually difficult for an individual to be awakened at this stage because the body becomes less responsive to outside stimuli.

Stage 4:

This stage is clearly referred to as the Delta sleep as the wave patterns are very slow and long. This is the stage where sleep is very deep and it is impossible for a person to wake up at this stage. The body becomes stiff, there is no eye movements, and it is the most relaxed state of sleep as it is the time when body repairs muscles and tissues, stimulates growth and development, boosts immune function, and builds up energy for the next day. This stage lasts for about 30 minutes. Sleep-walking and Bedwetting is common in this stage especially in children.

Stage 5:

This stage is also called as Rapid Eye Movement sleep. This is the time when people usually engage in dreams. Dreams are a mechanism to fulfil the unfulfilled wishes. The reason why this is called as the Rapid Eye Movement sleep is because in this stage there are several rapid eye movements as the individual is engaging in constant movie-like images that keeps playing in the brain. During this stage, the heart rate and blood pressure increase, and breathing becomes fast, irregular, and shallow. REM sleep plays an important role in learning and memory function, since this is when the brain consolidates and processes information from the day before so that it can be stored in the long-term memory. REM sleep is also referred to as paradoxical sleep because, while the brain and other body systems become more active, your muscles become more relaxed, or paralyzed. Dreaming occurs because of increased brain activity, but voluntary muscles become paralyzed. Voluntary muscles are those that you need to move by choice, for example, your arms and legs. Involuntary muscles are those that include your heart and gut. Sleep does not progress through all of these stages in sequence, however.

Sleep begins in Stage One and progresses into stages 2, 3, and 4. Then, after Stage Four sleep, Stages Three, then Two are repeated before going into REM sleep. Once REM is over, we usually return to Stage Two sleep. Sleep cycles through these stages approximately 4 or 5 times throughout the night. REM sleep usually occurs after 90 minutes of sleep. The first period of REM lasts for about 10 minutes, and it gets longer, and the final period lasts for about an Hour. The brain is very active at this stage.