Rapid Eye Movement (or REM), is the phase during sleep that involves active brainwaves with literally, rapid eye movement. Note, that it is incorrect to say “R-E-M” instead of pronouncing it literally “rem”. This is also called, Paradoxical Sleep, but Western nations usually just term this “REM Sleep”.
When Does REM Occur
REM takes place at intervals of about 90 minutes or more post falling asleep, while first going through 4 NREM (non-REM) stages of sleep. REM usually involves brainwaves that are similar to that of one who is awake. Beta waves are usually active during REM (out of alpha, delta, or theta).
REM usually starts out being 5 minutes long (unless there is a rebound), and they get longer as the night progresses to as long as a full hour. In a typical night’s sleep, the average person goes through at least 5 REM periods, and we wake up after each one, but are usually nearly impossible to remember.
In fact, when someone wakes up needing to use the bathroom, they never actually wake up to go to the bathroom for we can hold it all night. Unless they are woken up by some external variable (noises, movement, etc), we only naturally wake up because a REM period has ended. However, there are times when you can wake yourself up from sleep if you are lucid in both NREM and REM.
REM-rebound happens when someone is deprived of REM sleep, therefore, they usually occur much more quickly and last longer in order to make up for the lost time. The 1st phase of REM sleep will usually happen much quicker and last longer than five minutes, for example, depending on how much was lost.
REM sleep has been found to be often associated with dreaming. However, it is possible to dream during NREM, but the dreams are not usually vivid and may take on a 3rd person perspective. When we dream in REM sleep, we usually take on a 1st person perspective and dreaming is more vivid.
We need something to prevent us from acting out our dreams of course. The REM atonia phase prohibits the body from acting out dreams. This happens when motor neurons in the spinal cord become inactive, leaving us unable to move or else you would probably kick your bed partner every time you have a dream that involves running. This is not to be confused with sleep paralysis. Sleep paralysis is simply the experience of being paralyzed while assumed to be asleep.
Motor function is compromised due to REM atonia and the deactivated motor neurons where the brainstem and the spinal cord meet. If you think of the spinal cord (or vertebra) as the hallway that connects the brain to the rest of the body, then is would make sense that it would be impossible to move while dreaming. However, the brain can still send messages that signal respiratory or heart rate responses, which often relate to the dream. For example, an increased heart rate due to someone experiencing a nightmare.
REM Behavior Disorder
REM Behavior Disorder (or RBD), is a sleep disorder (more common in older males) that involves the REM atonia phase malfunctioning, resulting in the sleeper acting out his/her dreams. This is when the motor neurons are reactivated, resulting sometimes with hurting their bed partner, themselves, or destroying items on their nightstand.
This is not to be confused with sleep walking. Sleep walking occurs in stages 3-4 of sleep, while RBD obviously takes place during REM sleep. Plus, it is abnormal to dream while sleep walking.
Researchers knew that people suffering from RBD were acting out their dreams when their actions often correlated to what they claimed to be dreaming about.
Neurologists believe that we endure REM sleep to basically “defragment your brain” if you will. This is termed “Active Sleep”. It is important in brain development which organizes memory, function, psychology, etc. Those deprived of REM sleep, have shown behavioral problems, and permanent neurological problems in more rare cases. They also found that REM sleep occurs more in infants/new-born children, and gradually decreases and maintained into adulthood.
Those who work around the clock (fishermen, artists, etc), have found power napping to be quite helpful. This is because REM sleep is basically the sleep we really need to “recharge” as some would say. This involves being awake for a couple of hours, then getting about 30 minutes of sleep which about the last 25 minutes of it is composed of REM, and almost never getting more than 30-45 minutes.
Note that if you plan on trying this, remember that we also have NREM rebound and it can be very difficult to wake up if you get what is called a bonus nap. A bonus nap is getting more than what is recommended.
Exercise has been known to also increase the amount of REM sleep you get that night, which supports the theory that REM sleep is needed to regain energy.