Seasonal Affective Disorder in Detail

by Audrey Dusart, SUNY Cortland, December 23, 2004

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Are you sitting in your dorm room wondering why you feel so depressed? Are the days dragging on, each hour feeling the same as the last? Have you moved from a southern climate to a northern area that is now experiencing continual cloud coverage and dreary cold days? It wouldn’t be surprising if you are suffering from the symptoms of SAD. 

Seasonal Affective Disorder (SAD) is something that affects people who live in the upper latitudes where the weather changes from warm sunny days to cold, cloudy days.  When the weather begins to change around the month of September, most people become slower, more negative, and irritated by normal things that would otherwise not bother them during the spring and summer months.  These negative feelings normally last until the month of April when days are noticeably longer.(1) Students have the stress of exams, work schedules, and professor’s assignments constantly weighing down on them, not to mention a changing weather pattern.  Speaking as a student, there is enough stress to deal before adding cold, dark days to the package. Also, dorm rooms aren’t exactly the brightest places—they’re dark and dreary, small places even in the summertime.  It’s no surprise that many students feel the effects of SAD once fall kicks in.

SAD exists because of the amount of light that enters the eyes and the amount of chemicals produced by the brain as a result. When not enough light enters the eyes, an individual may experience mild to severe feelings of sadness. Some of these symptoms include sleep problems, disturbed sleep, early wake up, lethargy, overeating, depression, social problems, anxiety, loss in libido, mood changes, and a weakened immune system. Students who seek help for their depression during the winter months are often misdiagnosed: the depression they suffer from is not from anything other than SAD. All of these symptoms are controlled by the hypothalamus located at the base of the brain. Some people who experience SAD can only function properly if they are on some type of medication. Light therapy is the most widely used form of medication dealing with SAD.

The medications that are offered to help people with SAD include antidepressants such as Tricyclics, as well as Sertraline (Lustral), Paroxetine (Seroxat), and Fluoxetine (Prozac).(2) Psychotherapy and counseling are also offered to help lessen the effects of SAD as well as the herb St. John’s Wort, which is used in some countries to alleviate SAD symptoms.(3) 

However, light therapy seems to be the most commonly used form of medication when dealing with patients suffering from SAD. Doctors have reported that 85% of all people diagnosed with SAD receive light therapy.(4) Light therapy allows more intensified light to enter through the patient's eyes, therefore allowing the pineal gland to stop producing melatonin, which is a chemical produced in the brain that induces sleep, and this procedure allows for the patient to feel more energetic and positive. 

Melatonin is produced in excess in the winter months because there is a shortage of light, which is the switch that turns off the production of melatonin.(5) Nerve centers located in the brain are the controls that change daily moods and rhythms. These nerve centers are controlled by light.  Allowing enough light to enter the eyes allows the internal biological clock to function properly. Walking to class, even though it may be cold outside, isn’t such a bad idea if it’s sunny out; the more sunlight a person's eyes receive, the better any student will feel. 

A person undergoing light therapy only needs to be exposed to a light box for four hours a day. This can be done while working on homework, eating lunch or even watching TV. The intensity of a light box is 10 times that of a standard house lamp. This intensity is what tricks the brain into thinking that it is a clear sunny day in the middle of July.  July’s sun has the intensity of about 100,000 lux, while office or dorm lighting only gives off 200-500 lux. The treatment that is given to most people in light therapy is about 2500 lux; not exactly that of a clear summer day, but enough to make a considerable difference in the chemistry of the brain.(6) Most light therapy lighting systems cost between $200 and $300 and are easily found on the internet; a good Christmas present for anyone! (7)

This treatment is commonly used because of its accessibility and the short amount of time that it takes to begin alleviating the symptoms of SAD.  Most patients begin light therapy in early autumn, sometime around September and the effects are felt as early as 3-4 days later.  A patient doesn’t have to look straight into the light, although studies show that doing so would not affect the eyes in a negative way. Keeping a distance of 2-3 feet from the light box is enough to affect the patient positively. Because the intensity of a light bow is 10x that of normal house or office lighting, different glands in the brain continue to function producing chemicals as though the sun was still as intense as it was in the summer months.

Serotonin is the most important chemical produced in the brain when it comes to people affected by SAD. Serotonin is responsible for giving people the feeling of pleasure, and without moderate levels of it, a person will fall into depression. Light therapy and Prozac are given to patients affected with low levels of Serotonin.(8) Light is an environmental signal that is sent to the brain, which then proceeds to affect what is known as the Circadian Rhythm.(9) Circadian Rhythm is the biological clock inside the brain scientifically called the Hypothalamus Suprachiasmatic Nucleus (SCN). Without enough light passing through the eyes, the CR goes off balance and depression and anxiety among other negative effects occur. Also, without the right amount of light, one day could seem like two days because the CR is balancing, therefore making a person sleepy when they should be awake and vice versa.

The CR in anyone’s brain consists of three elements:

Input pathways that transfer light coming in through the eyes to the Hypothalamus.

The “pacemaker” itself, otherwise known as the hypothalamus.

Output pathways that transfer rhythm to the rest of the body therefore signaling sleep and wake times.

Scientists studying CR have found that all living organisms possess this biological clock through their genetic code. Given this knowledge, it can be said that even animals experience the affects of SAD. Hibernation is a way many animals deal with the changing seasons. Even the reproduction cycles of animals happen mainly in the spring when light intensity is climbing and daylight begins to last longer. Humans do not only feel the feelings of SAD; every organism will feel differently if the levels and intensity of light is altered for any amount of time. 

Taking walks on sunny days in the winter can help retrieve the feel good emotions of the summer; but still, SAD is something that will affect anyone living in a changing environment. Some people experience levels of SAD more than others, but overall, no one can escape the changes that are made in the brain when chemicals are over or under produced. Science has helped us discover why it is we feel the way we do in the winter months and what it is that we can do to stop our negative feelings. 

The next time you get a chance, take a walk around town on a sunny day for a few hours and soak up as much sun as you can. If there is snow on the ground already, the sunlight will be that much more intense. So get out there and take advantage of those winter rays as much as possible; a little bit can go a long way!

Sources:

1. http://www.nosad.org/

2. http://www.24dr.com/reference/library/psych/depression/sad.htm

3. http://www.healthy.net/scr/Article.asp?Id=463

4. http://depts.washington.edu/scc/sad.htm

5. http://www.apollolight.com/new_content/research/sad_ab_melatonin.html

6. http://www.diagnose-me.com/treat/T175911.html

7. http://www.apollohealth.com/golite.html?source+goaw&Kw+42d

8. http://members.aol.com/atracyphd/serotoni.htm

9. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/C/Circadian.html

DESIGNER:
Greg Montano, New Media Design, SUNY Cortland, USA

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