The Science of Sleep and Dreaming (Tentative Title)
Humanity has
been known [[better?]] dreaming since the beginning of its existence.
Dreaming was believed by some cultures to be a different reality, or godly revelations by others. What else could the early man hypothesize: all that was known is that a person would sleep through a portion of the day, have wondrous experiences, in many ways similar to wakefulness, and then wake up as if nothing had happened. Throughout history and all the ages, mystics, shamans, witch doctors
[[witch doctors? I wonder what Naiya meant]], yogis and
the like many others have attempted to understand sleep, dreams and their meanings.
Nathaniel Kleitman was a physiologist who established the world's first sleep laboratory in 1952 at the University of Chicago. He and a graduate student by the name of Eugene Aserinsky are considered
by some to be the fathers of
the study of sleep modern sleep research.
After hours of watching subjects sleep, Kleitman and Aserinsky
were able to find repeating patterns in sleep activity, when the sleeping subject would rapidly move his or her eyes. During this period, which Kleitman called "rapid eye movement" (REM), he observed a general increase in brain activity, and also that it was correlated with dreaming. This was the first solid step of scientific sleep research; ever since
their that discovery,
scientists were able to investigate the different patterns and stages of sleep to a finer degree, uncovering more about the nature of each stage.
Measuring brain activity in a sleeping person,
scientists it was discovered that sleep consists of repetitive cycles of brain activity
, during which you go through every important part of sleep. These cycles have. Each cycle has a duration of around 90 minutes, and changes slightly depending on how long you have been sleeping for.
The very first stage
of the cycle (N1) is not
necessarily yet sleep, but rather the beginning of
sleep it. It is a transition from wakefulness to sleep, often referred to as
somnolence. Slowly, brain activity lowers, and the brain enters the sleep process. This is the stage during which hypnic jerks occur.
The following stage
of the cycle (N2) is responsible for around 50% of total sleep. Muscular activity lowers and consciousness of the external environment disappears.
[[updating my own work, scientists no longer consider N3 and N4 different:]]
Stage N3 is often called "deep sleep". Brain activity, as well as muscle tone are the lowest. This is the stage in which night terrors, bed-wetting, sleep-walking and sleep-talking occur. Trying to wake someone up during deep sleep can be extremely difficult. It is considered essential for rest, and, together with the following stage (REM), will rebound in the next night if a person is deprived of them during sleep.
The final stage to mention is REM, or Rapid Eye Movement sleep. It is so called because of the rapid movements of the eyes during this phase. Mental activity rises and the brain behaves similar to that of a person who is meditating. For Lucid Dreaming, this is perhaps the most important sleep phase, as it is
theorized known that the majority of dreams occur during REM sleep. Furthermore, some neurotransmitters in the brain, such as serotonin, are completely shut down, thus inducing what is called
sleep atonia (popularly named Sleep Paralysis), during which motor functions do not work. The person is rendered physically motionless,
even if the brain commands the body to perform a movement. Based on that
knowledge comes a possible explanation of what dreams are.
This theory about dreams
is probably the most important one for our objective, which is lucid dreaming. It was given shape to by Dr. Stephen LaBerge, and will be explained below.
Our brain
always keeps an updated, functional image of our body at all times. This
body image, as it is called, allows us to, for example, know where our arms are placed without actually having to look at them; and to guarantee better muscular coordination for the body.
However due to sleep atonia, which happens in our sleep,
interestingly, even though the body image is still there, if you try to move, say, an arm, it will not move at all. But for the brain, it will be like it
had moved. The brain will update the body image, believing the arm has been moved, when actually it has never left its original position. The effect of this is that we can actually "move" our body image, without really moving our physical bodies.
We can walk around, jump, swim, or run, and everything will only happen inside our own head. Thanks to the highly
hallucinogenic imaginative state
that REM sleep gets us in, the brain is then able to actually make up what it would be seeing instead of
what it is actually seeing (the back of our eyelids) taking it from our senses.
This is how dreams work To make it short: you are able to move your body image without actually moving your real body, and your characteristic, imaginative mind fills in the details.
While we have begun to answer the question of how we sleep, unfortunately there is still no clear answer as to why we sleep. It is known that REM sleep--or dreaming sleep--is necessary for our bodies and minds to function.
Complete sleep deprivation can kill smaller mammals such as rats.
As humans, our body follows a natural daily rhythm - the circadian rhythm. It is thought that mammals were naturally selected to have an exact daily rhythm, which would offer them multiple advantages. To name a few; better metabolic and digestive activity, sleeping during the fixed time of the day which is least dangerous (either day or night, depending on the animal), knowing how much time there is left to perform actions such as hunt or travel, among others. A piece of evidence which strongly supports this is that the bodily rhythm is known to be affected by sunlight, or also artificial light - individuals wake up from sleep when exposed to light.
Rest is not a substitute for sleep. Because of this, scientists suspect that there are
specific things that sleep provides us which are fundamental. First one worth mentioning is that of neurological restoration: synthethizing more neurotransmitters and restoring sensitivity to neuroreceptors. Sleep has also been found to be fundamental for memorization and learning: humans subject to sleep deprivation have problems with memorizing new information and recalling memories. Also, humans put to sleep immediately after learning something new memorized the subject much more easily.
Sleep may also provide the body with a time to rest and heal. Continuous activation of the muscles would injure them just like overexertion would. Wound healing and immunity are also positively affected by sleep.
Children and babies require a lot of sleep to function properly (up to 18 daily hours, 8 of them being REM sleep). As humans grow older, they require each time less sleep, and the amount of REM sleep also decreases.
It has been pointed out that, if sleep were not essential, one should be able to find 1) animal species that do not sleep at all, 2) animals that do not need recovery sleep when they stay awake longer than usual, and 3) animals that suffer no serious consequences as a result of lack of sleep. Yet, no animals have been found to date that satisfy any of these criteria, which suggests that sleep is essential to the survival of complex species.
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[[I am adding some info info on dreams specifically; things I've posted here:
http://www.dreamviews.com/community/...7&postcount=31 (last subtitle). I do not know how essential this is - feel free to cut it out if it doesn't fit.]]
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Up to now, we have discussed sleep, its constituition and purpose. But we have said very little about actual dreams, which are our main objective. It turns out that dreams are still a mystery to science; the multiple theories concerning dreams reveal that little is actually understood about the phenomenon. What follows are the most prominent theories about the purpose of dreaming we have so far.
One theory proposes that dreams are the natural and random activation of some neurons in the brain during REM sleep, and as a response, the forebrain creates a story to situate and rationalize the nonsensical sensory information created.
Dreams have also been found to be related to memorization and learning. Individuals have reported dreaming about newly-learned subjects or activities in the first night. Riding a bike, travelling by boat or playing tennis may very likely induce a person to dream of those activities. Some specific dreams bring forth very distant memories, and also dreams that are highly emotional are very hardly forgotten.
Sigmund Freud hypothesized that dreams are the manifestations of subconscious thoughts and experiences, and suggested that dream interpretation could be a method of analysing the subconscious mind. Dreams would then reveal a person's fears, opinions, and desires.
Eugen Tarnow suggests that dreams are excitations of the long-term memory, in order to refresh memory and avoid forgetting of useful information. Dreams would then have a directly functional purpose.
A 2001 study showed evidence that illogical locations, characters, and experiences may help the brain strengthen the linking between otherwise distant or discrepant information. Dreams would then serve as a means to consolidate memories, find similarities and correlations between memorized information.
During the night there may be many external stimuli bombarding the senses; the mind interprets the stimulus and makes it a part of a dream, such as a sound, a voice, a light. A phone ringing may make a person dream of a phone ringing, and wetting the bed may make one dream of urination. It is not known if the brain does this to ensure continued sleep, or if the phenomenon is actually unintentional. The brain will, however, awaken an individual if they are in danger or if trained to respond to certain sounds, such as a loud noise or a baby crying.
Dreams may ultimately be a means of the brain to simulate and predict scenarios, which would train such ability to be used in real situations (music does exactly the same). This would be an evolutionary advantage, such as for hunting or fighting over territory.
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Final note: I think it would be
slightly better-flowing if we talked more to the reader. I think that right now it feels too formal. Perhaps it's just me though.
Sources:
http://www.uchospitals.edu/news/1999...-kleitman.html
http://www.nytimes.com/2003/11/11/sc...-we-sleep.html
http://www.camden.rutgers.edu/~bwhit...LEEP/index.htm
wikipedia - (Dream, Sleep, REM Sleep) accessed July 2009
