I. Introduction: a. Audience hook: Large portions of the population are affected by mood disorders. These mood disorders seem to be directly related to significant disruptions of both the circadian rhythm and the sleep/wake cycle (McClung, 2012). b. Thesis Statement: Research suggests the circadian rhythm is influenced by sunlight and regulates our mood. c. Preview of Main points: i. The circadian rhythm ii. The correlation between sunlight and mood swings. II. The location and function of the circadian rhythm.
(See visual aids attached)
a. The circadian rhythm is the name of the internal body clock of living organisms.
i. The internal body clock helps the body to adapt to the daily cycle of day and night. ii. The daily cycles involve “clock gens” which control the cycles in rhythmic waves. iii. Location of the master circadian is in the hypothalamus iv. Light is transmitted to the master circadian through the retina of the eye. v. The registration of light isn’t through conscious vision, but through rods and cones in the retina (Borvin, 2013) III. The correlation between (sun) light and mood swings. a. The hormone melatonin is used as the circadian marker. It is produced during the night and under absolute condition of darkness b. Inadequate light will disrupt the circadian rhythm and cause change in the release of hormone controlling brain activity. c. Change in melatonin release can cause sleep deprivation. Lack of sleep causes mood swings. d. Sunlight stimulates the retinal ganglion cells and causes them to produce melanopsin, which in its turn innervates the pineal gland to produce melatonin (Borvin, 2013). e. Not only the intensity of daylight, but also the duration of light exposure affects the circadian rhythm (Figuero, 2009) IV. Conclusion a. Restatement of thesis: Research suggests the circadian rhythm is influenced by sunlight and regulates our mood. b. Summary of main points: i. The circadian rhythm immediately affects daily cycles in the body ii. The availability and duration of light exposure through the retina impact our moods directly. c. Closing comments: i. It is important to have a balanced sleep-wake rhythm in order to prevent lack of sleep with as result depression and related mood disorders. ii. Improved technology enables us to imitate sun light, which gives us the opportunity to reduce disruption of the circadian rhythm when working in an environment without access to sun light.
Scripted Audience Questions
Question: Are mood swings seasonal?
Answer: The mood change is not as much depending on the season, as to the amount of light received in each particular season. Study has showed that most of winter depression is based on disrupted body rhythms (“Lighting and its Affect”, n.d.).
This makes sense considering the fact that we are hesitant to go outside during the day when it’s cold.
Question: How can we prevent disruption of the circadian rhythm?
Answer: - Intentionally create opportunities to be exposed to sun light. - Make simple adjustments of indoors lightning and create increase of exposure to light if there is no sunlight entry in your work area or living area (“Lighting and its affect”, n.d.) -
Question: What does this thesis mean in regards to the blind?
Answer: Studies have showed that about 50% of the researched blind are experiencing circadian rhythm disruption. The registration of light isn’t through conscious vision, but through rods and cones in the retina. For this reason the blind are still able to have some type circadian rhythm (Opthalmol, 1998).
References
Borvin. (2012). Circadian Rhythms: the effect of the light - Mental Health A-Z - Douglas Mental Health University Institute. (n.d.). Retrieved from http://www.douglas.qc.ca/info/circadian-rhythms-the-effect-of-the-light
Different Wavelengths Of Light Affect Circadian Rhythm. (n.d.). Retrieved from http://www.science20.com/news_releases/different_wavelengths_of_light_affect_circadian_rhythm
Disturbance of sleep in blindness. - PubMed - NCBI. (n.d.). Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/9822235/
How might circadian rhythms control mood? Let me count the ways….. (2013, April). Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3725187/
Lighting and its Affect on Your Mood. (n.d.).
Retrieved from http://www.nimh.nih.gov/news/science-news/2006/properly-timed-light-melatonin-lift-winter-depression-by-syncing-rhythms.shtml
Visual impairment and circadiam rhythm disorders. (n.d.). Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3202494/ SunSprite: A Wearable, Solar-Powered Light Tracker | Indiegogo. (n.d.). Retrieved from https://www.indiegogo.com/projects/sunsprite-a-wearable-solar-powered-light-tracker#/story
Visual Aid Script
Intensive research confirmed that mood swings can be correlated to the absence of or the insufficient amount of (sun) light. As Colleen A. McClung, 2012 and Diane Borvin, 2013 both have described the circadian rhythm is very susceptible to (sun) light and it instability often times manifests itself in sleep disorders, causing mood swings.
The retina of the eye plays an important role in keeping the cycle of the circadian rhythm constant, by producing melanopsin through the retinal ganglion cells, which innervates the pineal gland to produce melatonin.
Sources:
Manglapus, M. K., Uchiyama, H., Buelow, N. F., & Barlow, R. B. (1998). Circadian Rhythms of Rod- Cone Dominance in the Japanese Quail Retina. The Time Of Our Lives. (n.d.). Retrieved from http://learn.genetics.utah.edu/content/inheritance/clockgenes/ Intrinsically photosensitive retinal ganglion cells - Wikipedia, the free encyclopedia. (n.d.). Retrieved June 4, 2015, from http://en.wikipedia.org/wiki/Intrinsically_photosensitive_retinal_ganglion_cells https://www.indiegogo.com/projects/sunsprite-a-wearable-solar-powered-light-tracker#/story
The visual aid shows the path of the effect of light on the circadian master clock.
The retina catches light (sunlight or artificial light) and transmits it to the pineal gland, which is part of the hypothalamus. The absorption of this light doesn’t take place through the conscious vision, but is absorbed by the rods and cones in the retina 