What is sleep?
Before diving straight into what REM sleep is, it is best to understand sleep itself. We can always tell if someone is either sleeping or not. The common characteristics we subconsciously look for are…
- The person’s eyes are closed
- The person does not hear anything unless it is a sudden loud noise
- Breathing is slow and and rhythmic in pattern
- The person is completely relaxed and none of the muscles are tensed
- The person only moves occasionally, maybe once or twice in an hour
Sleep cannot only be measured by what we see, but we are able to understand what exactly the brain does when a person sleeps.
Using an electroencephalograph it is possible to measure brainwaves and brain activity while person sleeps from the moment they lie down to when they wake up the next morning.
If a person is awake and relaxed their brain generates alpha waves. Alpha waves are waves that have oscillations that are about 10 cycles per second.
If a person is alert then their brain activity is much higher than before. They are now generating beta waves that oscillate at twice the speed of alpha waves.
Sleeping produces different wave patterns from those when a person is awake. These patterns are slower than alpha and beta waves. The first wave pattern is theta waves. Theta waves oscillate between 3.5 – 7 cycles per second. The second, delta waves, oscillate at less than 3.5 cycles per second.
As a person falls deeper into sleep their brain activity patterns slow. As the brainwaves get slower it becomes harder to wake the person up from sleep.
One night of sleep is filled with cycles and stages. The two general categories of sleep are non-REM sleep and REM sleep. Non-REM sleep can be broken down even further into three or four sleep stages.
Being asleep isn’t one slow process, but rather it is a series of cycles that allow the body to get a full night’s rest while gradually waking up rather than suddenly wake up.
The first sleep cycle lasts normally around 90 minutes while the following cycles last 100-120 minutes. Though these numbers can vary upon the individual’s sleep patterns.
Each cycle begins and ends the same, but the time spend in each stage is different. A sleep cycle begins with non-REM sleep which is composed of stage 1, stage 2, stage 3. After entering stage 3 the body reverses the stages and goes stage 3, stage 2, stage 1.
Unlike when the person fell asleep when the body reaches stage 1 again it does not tell the body to wake up, but instead transitions into REM sleep before going through another cycle.
As the person sleeps longer time in each stage starts to shift and change until by the last cycle the body is in REM sleep most of the time just before the person wakes up.
Non-REM Sleep vs. REM Sleep
Non-REM sleep is short for non-rapid eye movement sleep. Majority of sleep time is spent in non-REM sleep, composing about 80% of average sleep time.
Non-REM sleep is dreamless, the breathing and heart rates are slow and regular, the person sleep is still, but not paralyzed.
REM sleep, however, is much different than non-REM sleep. REM sleep comprises the rest of sleep time, about 20-25%. At a young age the percent is much higher at 80% and as we get older the time spent in REM sleep is decreased.
REM sleep stands for rapid eye movement. This does not mean your eyes are open while you sleep. It means that they move quickly, but the movements are not consistent and constant. They are more intermittent. It is unknown exactly what the eye movements are for and what purpose they serve.
REM sleep has also been nicknamed “paradoxical sleep” because the body and brain is in a state that is very similar to being awake. The oxygen and energy consumption levels are high compared to other stages of sleep and sometimes higher than we are awake. Your brain almost reaches a stage similar to being awake while working on a complex problem.
During REM sleep your breathing becomes much more rapid and irregular. Your heart rate and blood pressure also increase similar to awake levels. The body’s core temperature is not as well regulated like before during sleep. The muscles become completely paralyzed and brain signals that control muscle movements are blocked.
The only brain signals that are not blocked are ones that control eye movements and other essential functions. This includes the heart pumping and the diaphragm expanding and collapsing allowing the person to breathe.
There are really no negative effects if you start to lack REM sleep, but it is found to be vital in someway. In the short term lack of REM sleep has been found to impair someone’s ability to learn and complete complex tasks. It has also been found to be a vital part in early childhood development.
If you are lacking in REM sleep the body may try to compensate for it. Your body will speed up the cycle stages and you will fall into REM sleep quicker and stay in that stage longer than normal.
REM Sleep Behavior Disorder
Some people suffer from RBD, or REM sleep behavior disorder. Unlike most people, these people are able to move and act out their dream that occur during REM sleep. They are able to move their limbs and get out of bed and sometimes engage in activities they would do when they are awake.
RBD is not like sleepwalking or sleep terrors. People who suffer from RBD can be woken up easily. When they do wake up they can clearly recall details of their dream.
Some of the most common actions with RBD are as followed
It is also very rare for a person to eat, drink, engage n sexual activity, or go to the bathroom when they suffer from RBD.