LIGHT
AND HUMAN EMOTIONS
A
Light,
whether natural or artificial, has physiological and psychological effects on
human beings. For example, adequate
exposure to the sun can increase the physical and emotional well-being of a
person. Physiologically, light is known to influence bodily processes that
regulate the most fundamental functions of the body, signifying just how potent
an effect it has on health. The circadian rhythm
adjusts to the environment through external cues, the most important of which
is daylight. Exposure to artificial light during the wee hours can trigger chemical changes and hormonal emissions that could cause an
imbalance. If this persists, the immune
system can weaken and various health problems may result. Skin flare-ups, migraine headaches, sleep
disorders, cataracts and macular degeneration, cardiovascular disease and even
cancer are just some of the conditions that can be caused or worsened by too
much or too little
light or exposure to light at the wrong time.
B
While much investigation into the physiological effects of light has
been carried out, little has been done on the potential it has to affect the
mood or temperament of a person. Indeed, the scientific community was initially
unconvinced about light’s mood-altering capacities. However, published studies on this subject have persuaded researchers of the validity of examining the effects of light on
emotion. For example, studies on seasonal affective disorder (SAD) have revealed that SAD is not some unusual malady
experienced only by few individuals but rather a recurring major depressive
disorder that is fairly common and that occurs at specific times of the year,
particularly summer and winter, and then abates as the season changes. Sufferers experience similar symptoms,
including oversleeping, fatigue and depression. Once SAD was accepted by the
medical community as a true disorder, effective treatments were sought, such as
light therapy and melatonin supplementation.
C
Apart from research on SAD, studies on the connection between light and
human emotions have been scant. The most recent inquiries involve colour
composition and brightness of light and their immediate effects on the
emotional state of a person. In the former, researchers hypothesized that light
acutely influences emotion even during short-term exposure. This was a compelling point because previous studies had concluded that light has an impact only after exposure has
occurred over an extended period of time. The research on colour composition
proved this to be untrue.
D
Colour elicits emotional reactions in people, a phenomenon considered
to be partly a result of cultural learning. In some countries, white is the
color of innocence, but in others, it is the color of death. Some studies,
however, explain that these reactions are innate rather than learned. For
example, the colours yellow, red, blue and green evoke certain responses in
most people—red is stimulating, green is calming, and so on. It would stand to
reason, then, that coloured light would also bring out an emotional reaction.
In separate studies conducted at research centers in Belgium, Switzerland and
England, researchers ascertained that the colour of light influences the way
emotional stimuli are processed by
the brain. Certain cognitive tasks routinely increase activity in specific
parts of the brain whereas other activities can decrease activity. When
activity increases, the activity is said to have an impact on the functional
organization of the brain.
E
In the coloured light experiments, volunteers listened to
angry-sounding voices and neutral-sounding voices while exposed to alternating
periods of blue and green light. Brain activity was recorded by magnetic
resonance imaging. When the volunteers were subjected to ambient blue light,
responses to the angry voices increased in the hippocampus, the amygdala and
that part of the brain where
voices register. This indicated the
functional connectivity of these parts of the brain that decode vocal
information. The results thus supported the assumption that even brief exposure
to blue light can have a profound impact on how the brain processes emotional
stimuli, activating and
strengthening the connections between areas of the brain that process language
and emotions.
F
Research on light intensity has also been sparse. The means for
substantiating the effects of bright light on mood were not available.
Moreover, response to light appeared to be highly personal and depended on
experience and cultural influences. Some early research deduced that it was
also based on gender, with women preferring dimly-lighted places and men
preferring brightly lighted ones. A study conducted at the UTSC this year was
premised on the theory that simply turning on the light can rouse a human
being’s emotional system. The main researcher, Alison Jing Xu, conducted six
studies and demonstrated that human emotions—both positive and negative—are felt
more intensely when a person is under bright light. Bright light is perceived
as heat, and heat is known
to trigger emotions. In Xu’s experiments, no matter what the stimulus was, bright light had the capacity to intensify a person’s emotional
reactions.
G
Participants
were exposed to different lighting conditions and then asked to respond to
different types of stimuli, such as a spicy sauce, negative words, positive
words, a fictional character, the appearance of a person, and two kinds of
juices. It was noted that the brighter the lighting, the more emotional the
response was. The participants were more likely to ask for more spicy sauce,
have extreme reactions to both positive and negative words, have more
aggressive feelings toward the fictional character, rate a person as being much more or much less attractive, and drink more
of the juice that they thought was tastier.
H
The results of the research have ramifications for various types of
situations. For example, if a business establishment wanted a stronger reaction to a new product, it
would be to their benefit to conduct a product launch in a brightly lighted
place. If a person was about to give bad news and wanted to tone down an individual’s reaction to the news, it would be good to dim the
lights.