Abstract

1. Conclusion Through this understanding of how melatonin is produced in the brain, and how simply being in a bright room can alter this, I am able to conclude that short light exposure will aid in treating Seasonal Affective Disorder. Abstract During the wintertime, when sunlight is sparse and the skies are mostly overcast, many people notice themselves becoming tired and depressed. These are symptoms of Seasonal Affective Disorder (SAD). The lack of sunlight causes our brains to release more melatonin, which causes us to become more lethargic, apathetic, socially removed, and eventually depressed. I hypothesize that light therapy for short periods of time will help to re-regulate the brain’s production and release of melatonin, thus improving the moods and resetting the biological clocks of people suffering from SAD during the winter months. Introduction When one thinks of nutrition, we may not realize that sufficient sunlight is a necessary component of a healthy life. Melatonin (fig. 3), N-acetyl-5-methoxytryptamine, a chemical produced in the pineal gland (Fig. 1), is important to many facets of human life; it is vital for the proper function of circadian and other bodily rhythms like sleep, puberty, and the regulation of gene expression in older people. My research focuses on melatonin and its effects on Seasonal Affective Disorder. I hypothesize that using light therapy to alter melatonin levels will positively affect depression levels in people with SAD. SAD is caused by a lack of sunlight, which usually occurs during winter when the days are shorter and often overcast and dreary. The lack of daylight in the winter makes it hard for people to wake up, causes them to sleep more, eat more (especially foods high in carbohydrates), gain weight, have trouble concentrating and become socially withdrawn and depressed. Light from our eyes travels through our brain and eventually reaches the pineal gland. When there is a lot of light, like during the daytime, the pineal gland releases less melatonin. When there is less light reaching the pineal gland, more melatonin is released and causes us to become sleepy. Studies have suggested that low concentrations of serotonin, a precursor to melatonin, in the brain are inked with depression (1). Serotonin is created in the brain in a long series of reactions involving a precursor compound, 5-hydroxy-tryptophan or 5-HTP, and a methyl donor, S-adenosyl methionine or SAMe (2). The concentrations of these compounds can affect the synthesis of serotonin. By increasing the synthesis, it may be possible to increase the concentration of serotonin in the brain which the brain will then convert into melatonin (fig. 2). Figure 2 Conversion of tryptophan to serotonin to melatonin Your Brain and the Winter BluesThe Effect of Melatonin on Seasonal Affective DisorderDanielle RaboldBeloit CollegeBeloit, Wisconsin Figure 4: depression scores and light exposure Figure 3 Molecular Structure of Melatonin Comparison between depression scores (and 95% upper and lower confidence intervals (CI) for baseline in dim light (1), after 20 minutes of bright light (2), 40 minutes (3) and 60 minutes (4) (p < .001). Means of depression scores and 95% CI Method For this project I read peer-reviewed articles. Results, Discussion The precursor to melatonin is serotonin, a neurotransmitter that itself is derived from the amino acid tryptophan. Within the pineal gland, serotonin is acetylated and then methylated to yield melatonin (3). The mechanism behind this pattern of secretion during the dark cycle is that activity of the rate-limiting enzyme in melatonin synthesis - serotonin N-acetyltransferase (NAT) - is low during daylight and peaks during the dark phase. (3) Looking at these factors of melatonin production, it would seem that by changing one’s diet, exercise regimen, sleep schedule, and adding light therapy to health maintenance, SAD can be regulated during the winter months. Kirk et al (4) also hypothesized that short exposure to light would aid in SAD. What they found was that indeed, light helps tremendously with SAD: the results state that after just one twenty minute treatment of light exposure, depression levels had dropped (as measured by a 24-item National Institute of Mental Health scale). After forty minutes of sitting with the light box, depression had dropped again. However, after 40 minutes the data plateaued and shows that exposure over 40 minutes is more effective than an exposure of 20 minutes but does not change after 40 (fig. 4). The exposure to bright light inhibited the release of melatonin in Kirk’s patients and lowered their depression noticeable after the first 20 minutes of exposure. Figure 1: the pineal gland of a horse in relation to the brain • Resources • Figure one: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/otherendo/pineal.html • Figure two: http://www.chembio.uoguelph.ca/educmat/Chm452/gif/seroton.gif • Figure three: http://php.med.unsw.edu.au/embryology/index.php?title=Endocrine_-_Pineal_Development • Figure four: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2913518/figure/F1/ • Stockmeier, Craig A. et al. “Increase in Serotonin-1A Autoreceptors in the Midbrain of Suicide Victims with Major Depression-Postmortem Evidence for Decreased Serotonin Activity.” The Journal of Neuroscience (1998). • . Mischoulon, D. Fava, M. “Role of S-adenosyl-L-methionine in the treatment of depression: a review of the evidence. “ American Journal of Clinical Nutrition (2002) . • R. Bowen. “The Pineal Gland and Melatonin”. March 17, 2003. • Virk, G. “Short exposure to light treatment improves depression scores in patients with seasonal affective disorder: A brief report”. PubMed. 2(009)