Sleep Stages

The stages of sleep can be broken down into two broad categories: non-REM and REM sleep. Non-REM (rapid eye movement) sleep can be further broken down into four more stages - stages 1-4.

Then you will move into stage two which includes sleep spindles and K complexes. Sleep spindles are very short bursts of brain activity, and K complexes are single high voltage strikes of brain activity. Also, in stage two delta brain waves start to slow function of the brain preparing for stage three and four. Stage three and stage four i will talk about as one because they are very similar and do similar things. These stages are referred to slow wave sleep because your brain is in it’s slowest speed of function. In stage three you brain is between 20 and 50 percent delta waves, from 50 to 100 percent delta waves you are considered to be in stage four. While in stage four people may experience sleep walking and other muscular movement without knowing so. Noises as loud as 90 decibels may not be able to wake the person from sleep. During REM sleep which is after NREM sleep the brain is more active and alert. This is where most dreams occur because your brain is active but you are still sleeping. After the short 15 minute period of REM sleep you will start over with stage one of NREM these cycles normally take 90 minutes to complete. Activity during sleep can come at any point but is most common in REM or stage four of

Sleep ===== If you attached an electroencephalograph to a person's head, you can record the person's brainwave activity. An awake and relaxed person generates alpha waves, which are consistent oscillations at about 10 cycles per second. An alert person generates beta waves, which are about twice as fast. During sleep, two slower patterns called theta waves and delta waves take over. Theta waves have oscillations in the range of 3.5 to 7 cycles per second, and delta waves have oscillations of less than 3.5 cycles per second. As a person falls asleep and sleep deepens, the brainwave patterns slow down. The slower the brainwave patterns, the deeper the sleep -- a person deep in delta wave sleep is hardest to wake

Typically, sleep occurs in five recurring sleep stages. Of these, four are stages leading up to REM sleep. REM sleep is an abbreciation for rapid eye movement. Neurotransmitters act differently on neurons in the brain, causing the mind to be awake or asleep. The neurotransmitters serotonin and norepinephrine keep the brain functioning properly when awake, however are less present when sleeping. Adenosine, a chemical, also is linked to drowsiness when present in the blood and is broken up when sleeping. Beta waves are the waves which occur in our waking state.

Stage two, or NREM-1 sleep, is the time where people often have hallucinations or feel as if they are falling, when in reality nothing is there and they are laying flat on the bed. This stage usually lasts about ten minutes. During this stage the muscles are still active and the eyes may still open and close occasionally. The breathing and heart rate of a person also slows when in NREM-1 sleep. Often, if a person is awakened during this stage they may think that they have not fallen asleep at all. NREM-1 sleep accounts for about 10% of the total night of sleep.

Like in the other stages of sleep, when we doze off and transition into a more powerful, restful, and peaceful sleep is when stage 3 and 4 finally begins. So, during these stages, we are hit with the deepest parts of sleep and while we undergo high delta waves and it can occur after 30 or 40 minutes of deep sleep. Moreover, while stage 3 and 4 hold some similarity due to the nature of the high level of delta waves that are occurring throughout this stage, it allows the person to experience a wholesome and powerful sleep. Finally, during the process of REM stage, most dreams occur and brainwaves revert to being small and fast. In doing so, they consist of tons of beta waves, which can also be seen while being awake. Also, it increases the respiration rate and could cause brain

This stage is believed to help people enter deeper stages of sleep (4). Stage 3 sleep consists of 20-50 percent delta activity and stage 4 sleep of more than 50 percents delta activity (4). Stages 3 and 4 are characterized as being slow wave sleep in addition to being the deepest levels of sleep. Approximately 90 minutes after being asleep, people enter rapid-eye-movement (REM) sleep (4). REM sleep consists of rapid eye movements, a desynchronized EEG, sensitivity to external stimulation, muscle paralysis and dreaming (4).

Narcolepsy is characterized my overwhelming sleep attacks, often, although not always, attributed to brain trauma. On the other hand, insomnia is characterized by the inability to fall asleep or stay asleep at night. Another sleep-related condition, sleep apnea, is the temporary stopping of breathing while one is asleep. An example of a very noticeable condition, night terrors are very common in certain demographics; children under age seven often express the screaming and thrashing behavior associated with this condition. These tremors often occur during NREM-3, whereas nightmares ordinarily occur during REM.

There are five stages of sleep. Each one is distinguishable from the others. During the course of a night’s sleep, on average, humans cycle through all of these stages several times, usually about 4 to 6 times. Circadian rhythms in the body tell us when it is time to sleep. Before sleeping, while alert, beta waves appear on an EEG. During a state of relaxation, immediately prior to sleeping, alpha waves appear on an EEG. After drifting off into sleep, the first sleep stage begins. This is characterized by being the lightest stage of sleep, with brain waves being slow and irregular. After drifting further to slumber, the second stage begins. Body temperature drops, and both heart rate and brain waves slow down. Breathing becomes shallow as well.

There are many sleep stages people go through when resting. The first sleep stage is the theta waves, also known as light sleeping. In this stage theta waves are increasing as the alpha waves fade out to put you into light sleep. If awaken from this stage most people are unaware they were actually beginning to sleep. Secondly you move on into the second stage, which is the sleep spindles. In this stage your temperature drops, heart rate slows, and your breathing becomes flat and irregular. Sleep spindles show up on paper as quick bursts of activity in the brain that last only a few seconds. During this sleep if you are awaken you will notice you were actually asleep. Next you have sleep stage three where the delta waves come in. Delta waves are the largest and slowest waves of them all; when a person hits this stage they are in the deepest stage of sleep. Lastly REM sleep is the final stage of sleeping. During this stage the body with go back through stage three and then through stage two to increase the body’s temperature. The eyes

Extremely slow brain waves, called delta waves, appear in stage 3, interspersed with smaller, faster waves. By stage 4, the brain exclusively produces delta waves. During stages 3 and 4 it is very difficult to wake someone up, this is called deep sleep. At this time there is no eye movement or muscle activity. The last stage is when we switch into REM sleep. Our breathing becomes faster, irregular, and shallow, our eyes jerk rapidly and different directions, and our limb muscles become temporarily paralyzed. As our blood pressure rises, our heart rate increases as well. At this stage the brain is most active and people experience vivid dreams. The sleep cycle lasts around 90 minutes and repeats between 3-6 times, depending on the person. During sleep, there is recovery of energy stores and thus restoration of energy balance. (Scharf, Naidoo, Zimmerman, &Pack,

This stage is where we can be woken up the easiest. Stage 2 is where our brain activity and eye movement start to slow down and stop. Stage 3 brain waves start to begin with slow and fast movements. Stage 4 also known as deep sleep is the toughest stage to wake someone up. It is the stage where there is no eye movement or muscle activity and if you were to awaken during this stage. The results would be the feeling of grogginess

The first four stages are preparing the body for the last stage which is REM. These stages slow down the brain waves and stop the eye movement; stage four and three are known as delta sleep and during this stage the brain produces delta waves. Delta waves are the lowest out of the frequencies and occur during dreamless sleep. They are used to recover unavailable information that people cannot receive when they are awake. This leads to the REM cycle of sleep where all dreaming occurs. In the REM cycle the brain paralyzes our bodies so that people cannot move. When people first figured out what REM was they didn’t know that our bodies were paralyzed during the stage. The National Sleep Foundation has also been discovering more new things within this discovery. After the REM discovery, people recognized that brain activity during REM resembles wakefulness. People are paralyzed and experience no muscle movement(“National Sleep Foundation”). They have concluded that the REM stage indeed does put us through paralyzation during our sleep, but that's not the only thing our bodies do during REM. During the REM stage of sleep breathing become more irregular, more rapid, and shallow. Eyes jerk rapidly in various directions. Our blood pressure rises and heart rate increases. Our bodies are pretty much awake when we are in this stage(“What Are Dreams"). Usually someone wouldn’t expect this during sleep but this proves that our bodies are just as awake when sleeping than when they actually are awake. The brain and heart act the same way and so do our eyes (just not as slow moving). When someone is awoken during this stage they feel as if they had just experienced the dream in real life. They then realize that it was just a dream by remembering impossible things that couldn’t happen on earth. Because of this discovery of REM scientists can use this information to help figure out why we dream. Maybe they can

There are two kinds of sleep: rapid eye movement (REM), and non-REM (NREM) sleep. Within NREM sleep there are four stages: NREM stage 1, 2, 3, and 4. While in REM sleep the brain is incredibly active, doing all of the things that it normally does during the day, such as eating and walking, as it interprets and sorts through information from the day, but the body is in a state of paralysis because the pons is suppressing the signals that the motor cortex is sending to the voluntary muscles. In an alert person the brain is producing beta waves. These waves are short and fast. When a person is still awake, but relaxed the brain slows down to alpha waves, which are still recognizable as being awake, but significantly slower than beta waves. The next stage of sleep is non-REM 1. In NREM 1 the relaxed-but-awake alpha waves are gradually replaced by theta waves. If awoken while in NREM 1

Parasomnias – These are unusual experiences or behaviors that occur during sleep; they include sleep terror disorder and sleepwalking (which occur during stage 4 sleep) and nightmare disorder (which occurs during rapid eye movement [REM] sleep).