Light and Dark:Its Impact on Brain

The significant factor that plays a role in the physiological processes of almost all living organisms is the 24-hour cycle known as a circadian rhythm, based around the night-and-day cycle of the Earth. In humans and other animals, different brain chemicals are released on account of the presence or absence of light. One such brain chemical is melatonin, which serves to induce sleep by causing a drowsy state within the individual. Melatonin begins its release as the environment becomes darker, but subsides as it becomes brighter. When melatonin‘s production is not shut off completely within the system such as on an overcast day, a person‘s system remains in a depressed state, whereas on a sunny day, light shuts down the production of melatonin causing a more active state. The effect that light has on our brains is so instinctual that common culture has symbolized happiness with sunshine and sadness with rain and clouds.

Likewise, flowering plants will either not flower at all or not as effectively, if they are not provided with the appropriate night-and-day cycle. Even two minutes of light during the ―night‖ cycle can harm a plant or even prevent flowering.

"Businesses take advantage of the effects of light by calculating the ideal brightness of the lights in their stores and offices so as to increase sales and productivity"

A perfect illustration of the effect light has on the nervous system can be seen in species of bears who live in temperate climates. When winter comes in this type of climate, bears not only become less active but go into a long hibernation, or period of greatly reduced activity. It is the internal mechanisms of the brain itself that control this behavior within the bear, due to the reduction of light during the winter months as well as several other factors.

Many people in colder, darker climates such as in Scandinavia, which has one of the world‘s highest suicide rates, experience a disorder known as Seasonal Affective Disorder, or SAD. SAD is caused by the extended hours of darkness and is depression that is caused by a lack of light. The usual treatment for SAD is exposing the individual to a sunlamp that emits all of the wavelengths present in regular sunlight, for a duration of 30 to 60 minutes per day. With this treatment, 80% of the individuals benefit to some degree, including 50% who fully recover from their SAD-induced depression.

Businesses take advantage of the effects of light by calculating the ideal brightness of the lights in their stores and offices so as to increase sales and productivity. Conversely, the ―mood‖ lighting used in certain restaurants, and in any other venue trying to induce a romantic setting, helps achieve its purpose by inducing a feeling of isolation for a couple from the rest of the world, as well by neurologically inducing the minds to utilize their own calming chemicals.

Additionally and quite obviously, one‘s personality also plays a vast role in one‘s processing of information, thoughts, mood, and consciousness. Little is understood as to the physiology behind personality, as the psychological sciences understand only the basics at this time, but the effects of personality on the individual‘s world are immense. The effects of being either extroverted or introverted are prime examples. Extroverts tend to be more optimistic than introverts because human beings obtain many forms of happiness through social interaction. An introverted person, conversely, most likely sees things more pessimistically because the introvert is continually at odds with the world due to the fact that social interactions pose more of a challenge to them.

The sense of self, together with all of its implications, is so unconsciously ingrained in the mind that even amnesiacs,people who lost the ability to retrieve various parts of their memory, can still report what they are like. Even amnesiacs who have no recollection of anything that has occurred throughout their entire lives, including events that have just occurred but that are no longer in their short-term memory, are still able to say with a high degree of accuracy who they are. This seems to suggest that one‘s personality exists so strongly within one‘s being that it is detached, to a certain extent, from the events of one‘s past. It is internalized, and is therefore so much a part of the Self that everything that one experiences is completely colored by who one is.

(Taken From 'A Brief Guide to to Understand Everything' by 'Max Mische')

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