Chapter 9: Indications of Light and Stress

In Chapter 9, everyone had the sudden freedom to go outside of the mansion. This surprised me the most because of the innocence in the request, going outside to check on Cesar, and how easily the Generals complied. Everyone seemed more than happy to enjoy this sudden change in routine as they quickly adapted different activities. What are the possible effects of exposing the human body to natural light.

Exposure to daylight has been proven in several studies to have positive therapeutic effects on patients with mood disorders like depression. Daylight exposure can induce neuroendocrine changes can alter mood as it modulates the pituitary and pineal glands. Light activation causes decrease in melatonin, norepinephrine, and acetylcholine. These neurotransmitters are involved in regulating sleep and “mood dampening” effects. On the other hand, light activation effectively increases cortisol, serotonin, GABA and dopamine levels. These neurotransmitters are involved in motivation, mood and wakefulness.(4)

Alimoglu found similarities between mood disorders and burnout. Burnout was first termed by Herbert Freudenberg in 1974 in reference to the “prolonged psychological response to chronic emotional and interpersonal stressors on the job, and is defined by the three dimensions of emotional exhaustion, depersonalization, and lower personal accomplishments.” More precedence was placed on emotional exhaustion due to its implications of general stress on the human mind and body. Therefore, it was a key factor in their study. I found it interesting that they specifically mentioned stress here because of how stress is most likely to be the most prevalent problem in our society, as a result of long working hours involved with being a student or employee. Alimoglu focused their study on health care providers, considering that they are one of the groups that experience high work stresses and burnouts. Nurses are especially susceptible to moderate-to-high burnout levels. This study found despite the lack of direct effect on burnout, daylight exposure proved to have positive effects. Alimoglu’s findings determined that at least 3 hours a day of daylight exposure significantly decreased stress and produced higher job satisfaction.(2) So what is causing this sudden boost of energy or positive emotion (satisfaction and happiness) in the participants?

My research leads me to the effects of cortisol. Cortisol is a useful hormone to have in response to stress and is a great contributor to our survival because it can temporarily increase energy production and usage especially during “fight-or-flight” situations.(1) Knowing this, I initially thought that the higher production of cortisol has great benefits! The more energy you have at your disposal could, in effect, lead to greater productivity when completing more tasks throughout the day. However, Aronson suggests quite the opposite. In fact, she reasons “with our ever-stressed, fast-paced lifestyle, our bodies are pumping out cortisol almost constantly, which can wreak havoc on our health.” (1) Chronic elevations of cortisol secretion in the body have been found to correlate with diabetes, weight gain and obesity, among other things.(1) I have always wondered about the significance and implications of the production of cortisol in our body. These studies only served to further add to my many inquiries. Cortisol can have serious implications to our health and longevity as it helps our body manage with the stresses in our daily life.

This led me to a very interesting study conducted by Kuller on the placement of children in classrooms with and without windows. This study is specifically catered to find a possible correlation between natural light exposures on the production of stress hormones. The study used natural light vs. two types of fluorescent light. It then used the production of cortisol, a stress hormone, as an indicator of the light’s effects on the human body. Significantly, Kuller observed significant changes in cortisol levels from the classrooms tested over the span of four months (September, December, February and May) as the body responds to the annual variation, with an intervention of having or lack of windows in the classrooms. The secretion of cortisol gradually declined from high levels in September to a minimum in December. These levels then increased from February to May. There are also implications of children from northern hemispheres producing more stress hormones in the summer than in the winter. I believe that this is likely due to the more lengthy periods of the lasting cold seasons up north therefore there may be a more significant lack of daylight in those states. Classroom A had normal windows and had the highest overall levels of cortisol produced among the children. In contrast, classroom C lacked windows and daylight tubes (acquired the least amount of daylight) so their cortisol levels dropped even after December and didn’t reach the minimum until February. This indicates that the body’s annual response is delayed due to the absence of daylight.(3) I believe that our body has great dependence on visual cues provided by light to regulate hormone production and maintain our body’s circadian rhythm.

In conclusion, my findings set me off to further inquiries and avenues about cortisol. For instance, how are college students’ cortisol levels affected their academic environment? Are people constantly working in settings that impedes exposure to natural light more vulnerable to developing depression secondary to the lack of satisfaction or motivation? Furthermore, which occupations in our work force experience constant and the highest levels of stress? Is there a significant difference in stresses between different countries and how are they managed? What other methods can we use to cope or decrease stress in the workforce?


  1. Aronson D. Cortisol — Its Role in Stress, Inflammation, and Indications for Diet Therapy. Today’s Dietitian. 2009; 11 (11): 38.
  2. Alimoglu MK, Donmez L. Daylight exposure and the other predictors of burnout among nurses in a University Hospital International. Journal of Nursing Studies. 2004:42; 549-555.
  3. Kuller R, Lindsten C. Health and Behavior of Children in Classrooms With or Without Windows. Journal of Environmental Psychology. 1992; 12: 305-317.
  4. What are Neurotransmitters? Neurogistics. 2015.

2 thoughts on “Chapter 9: Indications of Light and Stress

  1. dgromels says:

    Hello Hannah,
    I very much enjoyed reading your blog post after talking to Colin in class, as he explored a similar line of research in his posting this week. I was surprised to read about the Kuller study that found that students in classrooms with windows produced more cortisol because I usually feel less stressed when I am working near natural sunlight than I do in a room with fluorescent bulbs. I would be interested to look at how cortisol production relates to the release of serotonin in the brain. My mom has Seasonal Affective Disorder (SAD) and either has to sit outside or beside a special light-therapy lamp that mimics the sun in order to increase the production of serotonin during the fall and winter months. It seems counterintuitive that this could result in the release of higher amounts of cortisol and make her more stressed, but at the same time lighten her mood.

    At the end of your post, you mentioned the relationship between natural light and our circadian rhythms. Since we “fell back” for daylight savings time a few days ago, it made me think about how this practice might affect our hormone levels. Every year, articles come out expressing dissatisfaction with daylight savings time, arguing that it not only is a hassle, but it also has a high economic cost due to lost productivity. I wonder if it affects mental health at all. Do we become more stressed out because we are receiving more or fewer hours of sunlight when the time changes? Perhaps this could become another complaint against daylight savings time and move the government toward the decision to get rid of it.


  2. Michael Pedersen says:

    Very interesting blog post this week!

    In particular the mention of how melatonin and other neurotransmitters regulate sleep reminded me of a study involving how living in a cave influences sleep cycles. In particular this experiment involved an individual going into a cave and living there for six or so months. The experiment resulted in the subject’s sleep cycle turning into a 48 hour cycle. This dovetales into the Kuller research exploring cortisol levels in students by implying prolonged low levels of coriisol and as a result stress could be a major factor altering sleep pattern. If you wanted to explore a slightly different avenue of research this would definitely be an interesting space to look into. [1]

    Your research into cortisol and its effects was also quite intriguing. Specifically, the body’s perception of time is of great interest since, similar to the aformentioned cave study, the body’s internal circadian rhythm could be influenced somewhat. Thus, I wonder if to what extent this has on human growth development during childhood onto the early teen years. Studies would probably be difficult to find given the timescale involved but the idea that the body’s biological clock, and in relation the body’s accumulated stress, could decrease through lack of visual indication of the seasons.

    In general, this blog post really made me wonder about how much the body is influenced by the seasons and how lack of seasonal cues could reduce stress and thus slow a body’s biological clock. By understanding the body’s needs and tendencies to environmental factors we can optimize our world to even better suit human needs.



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