Seasonal Affective Disorder (SAD): Causes, Symptoms, Treatment

If you experience depression solely in the winter months, you may have a condition known as seasonal affective disorder (SAD), also referred to in layman’s terms as “seasonal depression.”  Throughout human evolution, it was speculated that mood changes occurred during inclement conditions such as winter months due to the fact that in these conditions, it was difficult to attain food and most obviously – adequate sunlight.

Exposure to sunlight is important because it helps regulate the body’s circadian rhythm or “biological clock.”  Sunlight exposure during the day helps promote vigilance, vigor, and has an energizing effect.  However, lack of sufficient sunlight can have major neurophysiological implications, including causing psychological conditions (e.g. depression) and a host of other medical problems.

Individuals with seasonal affective disorder (SAD) tend to only become depressed during the winter months, but usually “snap out” of their depression in the spring – when sunlight returns, flowers start to bloom, and the air changes.  Assuming the individual with seasonal affective disorder is geographically located in a climate with long winters, they can expect suboptimal dysphoric moods to perpetuate during these months.

A Brief History of Seasonal Affective Disorder (SAD)

The first research of seasonal affective disorder in the United States was spurred by Herb Kern in the late 1970s.  Herb Kern worked as a research engineer and noticed that during the winter months, his mood became increasingly depressive.  He logically speculated that lack of light in the winter was the cause, and mentioned this to the National Institute of Mental Health (NIMH).

The NIMH was interested in “winter depression” and designed a customized “light box” to emit bright light for Herb Kern.  Within just a few days of using the light box, Herb noted that he felt significantly better; his mood had improved and the depression had lifted.  By the 1980s, seasonal affective disorder (SAD) was formally acknowledged by the National Institute of Mental Health.

Herb Kern wasn’t the only professional coping with the “winter blues.”  A doctor named Norman E. Rosenthal and his colleagues brought further attention to the condition.  Doctor Rosenthal had suffered from depression himself during harsh winters in the Northern region of the United States.  Like Kern, Rosenthal also speculated that the cause of his “winter blues” stemmed from reductions in natural light exposure during winter months.

Despite the fact that he had personally experienced seasonal affective disorder (SAD), there was limited mainstream research in support of the condition’s existence and possible treatments.  To further investigate seasonal affective disorder, Rosenthal et al. conducted a placebo-controlled study in 1984 using light therapy as a treatment.  In the experiment, he analyzed 29 patients that suffered from winter depression – characterized by excessive sleepiness, overeating, and carbohydrate cravings.

The symptoms were directly associated with changes in climate and latitude.  Administration of bright artificial light was noted to yield an “antidepressant effect” on these individuals.  Despite early research by Rosenthal, some still believed that seasonal affective disorder wasn’t a valid diagnosis.

That all would change in 1993 when Rosenthal’s book “Winter Blues” captured mainstream attention, highlighting the legitimacy of the condition.  These days it is well accepted that seasonal affective disorder is a condition that causes many individuals to feel increasingly depressed and moody during winter months.

• Source: https://www.ncbi.nlm.nih.gov/pubmed/6581756
• Source: https://books.google.com/books/about/Winter_Blues.html

What is Seasonal Affective Disorder (SAD)?

Seasonal affective disorder was initially reported as a “syndrome characterized by recurrent depressions that occur annually at the same time each year.”  While seasonal affective disorder is most commonly experienced during winter months, one common misconception is that everyone experiences seasonal affective disorder in the winter.  The word “seasonal” implies that a person could theoretically experience it at anytime of the year, including the summer.

Various names for seasonal affective disorder include winter depression and winter blues, but also – summer depression, summertime sadness – or just “seasonal depression.”  Seasonal affective disorder implies that a person has normal mental health during a majority of the year, but during one particular season (e.g. the winter) they develop depression.

According to the DSM (Diagnostic Statistical Manual of Mental Disorders), seasonal affective disorder is regarded as a seasonal subtype of “major depressive disorder.”  In the past it was classified as a “unique mood disorder.”  Within the United States, it is thought that the state most plagued by seasonal affective disorder is Alaska, with nearly 10% of residents experiencing the winter blues.

Seasonal Affective Disorder Causes (List of Possibilities)

There are a variety of potential causes of seasonal affective disorder.  In most cases, the causes are subject to individual variation.  A person experiencing depressive symptoms solely in the summer (i.e. summertime sadness) probably has a different causes than someone experiencing depressive symptoms solely during the winter.  While sunlight may be a highly influential factor in cases of winter seasonal affective disorder, it may not be the only cause.

Brain waves: A lack of sunlight is known to trigger neurophysiological changes, one of which is thought to be brain waves.  Brain wave changes have been noted among those with seasonal affective disorder, particularly during sleep stages.  Individuals with winter depression tend to have less delta waves, ultimately compromising their ability to enter deep sleep.

It could also be speculated that people with seasonal affective disorder may be lacking sufficient beta waves as a result of a cascade effect (lack of sunlight, results in neurohormonal changes, which changes daytime brain waves).  Perhaps excess slow wave activity in the theta range or alpha range during the day may exacerbate seasonal affective disorder.

Circadian rhythm disruption: When a person isn’t getting enough light during the day (or too much at night), it throws their circadian rhythm out of homeostatic balance.  This results is suboptimal production of various hormones, neurotransmitters, and has detrimental effects on health.  Individuals not getting enough sunlight may end up with high melatonin during the day; making them feel constantly drowsy or prone to hypersomnia.

Bright light therapy is known to help correct circadian rhythm disruptions and an effective intervention for seasonal affective disorder, highlighting the likelihood that a lack of daytime sunlight causes circadian rhythm disruption, which then triggers a cascade of other neurophysiological changes.

Evolutionary adaptations: Throughout the evolution of humanity, food was a scarce commodity.  During the winter months, it was thought that in order to survive, humans reduced food consumption and traveled less frequently.  While they didn’t go into “hibernation” like other creatures, they weren’t burning as many calories, which reduced their need for food.

The reduced food consumption may have caused humans to feel more depressed during these months.  Others speculate that since seasonal affective disorder is more likely to affect women than men, it may be an evolutionary adaptation related to reproduction.  The moodiness associated with seasonal affective disorder may prevent births during harsh winter conditions.

Genetics / epigenetics: It is important to consider the fact that certain genetics may be more associated with seasonal affective disorder than others.  Not everyone experiences seasonal affective disorder or a low mood during the winter.  Part of this may be due to certain genes and expressions that influence low mood as a result of seasonal changes.  Further research is warranted to better understand the genetic risk factors for seasonal depression.

Icelandics seldom experience seasonal affective disorder and are considered an exception to the finding that residents of Nordic countries experience seasonal depression at higher rates. Icelandics likely have different genetics that make them resistant to mood changes with the season.

Hormones & Neurotransmitters: Environmental changes that occur during certain seasons like the winter can alter neurotransmission.  When you aren’t getting enough sun over a long period of time, the pineal gland may be overproducing melatonin or manufacturing it at suboptimal times of the day.  This may in turn affect a variety of other neurohormones and neurotransmitters.

Another theory is that seasonal affective disorder may be linked to low serotonin levels and other serotonergic abnormalities.  Since melatonin and serotonin are closely related, changes to production of each may be caused by one factor such as lack of sunlight, and exacerbated by their symbiotic relationship (e.g. lack of serotonin often means less melatonin).  It should be understood that seasonal depression is not limited to melatonin and/or serotonin – other neurotransmission may become altered as well.

Junk food consumption: One fast-track recipe for depression is to eat nothing but junk food during the winter months.  Since food was scarce millions of years ago, humans needed to eat whatever was available.  Now that food can be attained from any local grocery store, is designed to be addictive, and is filled with chemicals – people eat more of it than usual.

During the winter months, people often eat more junk food and move around less; toxins accumulate in their body from this consumption and they become depressed.  Rather than eating an optimized diet for depression, people are eating diets that exacerbate their depression and accumulate more toxins as a result of sedentary behavior.

Lack of sunlight: Perhaps the most cited cause of seasonal affective disorder is lack of natural light.  The reason many experts suggest that a lack of light causes this condition is due to the fact that bright light therapy is considered an effective treatment for the winter blues.  Arctic regions tend to have higher rates of seasonal affective disorder compared to locations near the equator with an abundance of year-round sunlight.

Sedentary behavior: Many humans become more or less active during certain months of the year.  Those suffering from seasonal affective disorder may become significantly less active during the winter months.  This inactivity or sedentarism is often a result of inclement weather, lack of available outdoor activities, and the fact that most people prefer the comfort of their warm homes over harsh, snowy, cold conditions.

This sedentary behavior can detrimentally affect cognitive function, neurotransmission, and allows the body to accumulate more toxins from food; all of which are likely to cause seasonal depression.  Despite the fact that the sedentary behavior may be caused by something such as low energy from lack of sunlight, it can end up worsening the condition.

Sleep abnormalities: The sleep abnormalities associated with seasonal affective disorder may be due to the fact that the circadian rhythm is disrupted as a result of poor daytime sunlight.  The cascade of physiological changes that stem from lack of sunlight include abnormalities with melatonin production and possible neurotransmitter imbalances.

It has been shown that those with seasonal affective disorder have a longer sleep latency (it takes them longer to fall asleep) and reduced restorative deep sleep.  These sleep abnormalities may further reinforce the seasonal depression.

Vitamin D deficiency: There have been numerous reports linking vitamin D deficiency and depression.  In the winter months, it is difficult for humans to attain sufficient vitamin D unless they own a tanning bed or take supplements.  It should be clear that the most efficient way to attain vitamin D is exposure to sunlight; you can tell if your vitamin D levels are adequate based on whether you have a healthy tan or are pale as a ghost.

During the winter, a lack of sunlight naturally cuts your supply of vitamin D, ultimately impairing many biological functions.  It is possible that deficiencies in vitamin D could trigger depressive symptoms.  That said, it is more likely that a lack of sunlight is the culprit for seasonal depression rather than low vitamin D.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/15927269

Considering the synergistic effect of multiple factors…

It cannot be assumed that there’s one universal culprit for causing seasonal affective disorder.  Since the condition can manifest in the summer months associated with bright light, various behavioral and environmental factors may influence cases of summertime depression.  That said, it is relatively apparent that most individuals suffering from seasonal affective disorder end up with winter depression.

In cases of winter depression, the most probable cause is lack of sunlight exposure.  The lack of sunlight exposure could: disrupt the circadian rhythm, result in chemical imbalances (hormones, neurotransmitters, etc.), cause low vitamin D levels, and epigenetic changes that exacerbate depressive symptoms.  It is important to consider the fact that the exact causes of seasonal affective disorder may be subject to individual variation.

In other words, for one person the depressive symptoms may be caused solely by a lack of bright light, while for another person, the depressive symptoms may occur based on genetic/evolutionary tendencies.  For a third person, a combination of sedentarism, poor diet choices, and staying cooped inside all day may trigger depressive symptoms.

Consider the synergistic effect of multiple causal factors.  Most people feel depressed when they eat junk foods and remain inactive.  However, now add to the fact that the person is getting no sunlight, which triggers detrimental neurophysiological changes.  The combined effect of junk food eating, inactivity, and sun-deprived neurophysiological alterations could trigger a very severe seasonal depression.

Seasonal Affective Disorder Symptoms

Below is a list of symptoms you may experience if you have seasonal affective disorder.  It should be understood that the number and severity of symptoms experienced will be largely subject to individual variation.

• Anxiety: It is more common for people to experience heightened anxiety during cases of summer-induced seasonal affective disorder compared to that which occurs during the winter. That said, anxiety is a symptom that has been associated with seasonal affective disorder, but isn’t considered quite as common as some of the other symptoms.
• Appetite changes: Many people report experiencing appetite changes, especially during winter depression. These appetite changes are most often characterized by increases in hunger and an inability to stop eating.  It is thought that an increased appetite may serve as a coping mechanism for the depressive mood.  It should be known that appetite could also decrease and a person may feel less hungry than usual.
• Brain fog: A common symptom associated with depression and seasonal blues is that of brain fog. A person may have a difficult time thinking clearly and may feel as if they cannot organize their thoughts for planning.  They may also have a difficult time engaging in critical thinking tasks.  This brain fog may be a result of neurophysiological changes associated with lack of sunlight and excess theta waves.
• Cognitive impairment: When a person becomes depressed, their cognition often becomes impaired. When depression is left untreated, a person’s brain isn’t working as efficiently as it could be and they stay “stuck” in a state of suboptimal mental performance.  Depression slows psychomotor activity, arousal, and production of neurotransmitters than enhance cognition.
• Depression: The most notable symptom of seasonal affective disorder is a depression that occurs during the same season each year. This depression may be severe to the point of triggering suicidal ideation, or may be relatively minor.  In any regard, the depression caused by seasonal affective disorder is typically the most problematic symptom.
• Fatigue: Individuals experiencing seasonal affective disorder often experience severe fatigue, almost like a seasonal “fatigue” disorder. The fatigue is likely to stem from a lack of sunlight, which results in excess production of melatonin – making you feel drowsy with low energy.  Add a depressed mood to the equation and the fatigue becomes exacerbated.
• Food cravings: It is common to experience major food cravings with seasonal affective disorder, especially during the winter months. Most of these cravings are for simple carbohydrates or sugary, floury, and highly processed foods (e.g. cookies).  When we eat these foods, we often crave more and the cycle perpetuates.  Not only are these foods detrimental to our health, but they perpetuate our depression.
• Hopelessness: When you’re depressed, regardless of whether it’s seasonal or not, you may feel hopeless. This hopelessness can result from a number of factors including imbalances of hormones and neurotransmitters, abnormal sleep patterns, and social withdrawal.  In the case of seasonal affective disorder, this hopelessness diminishes and subsides when the seasons change.
• Insomnia: As your circadian rhythm gets thrown off balance as a result of inadequate daytime sunlight, your sleep cycle often becomes chaotic. This may lead a person to experience drowsiness or sleepiness during the day, but insomnia at night.  Insomnia may be more likely to occur among individuals that experience anxiety or feel stressed in addition to depressed.
• Low energy: It may seem impossible to summon up the energy to complete any task. As a result of seasonal affective disorder, your productivity may take a major hit, making it difficult to perform at school or work-related functions.  There is an association between lack of bright light during the daytime and reduced arousal, which is likely why people notice their energy levels plummet in the winter months.
• Low libido: Some people with seasonal depression notice that their sex drive takes a major hit. They may be uninterested in having sex with their significant other and/or end up dealing with anorgasmia (inability to orgasm).
• Mood swings: Many people notice that they become irritable, angry, and unpleasant during the winter months. Some of this may be an evolutionary or genetic response to seasonal change.  That said, it’s relatively difficult to stay in a good mood when you haven’t been exposed to sufficient sunlight in weeks (or perhaps months).
• Nausea: It has been reported that some people experience nausea, or feel as if they are on the verge of vomiting during certain seasons. This nausea may be related to a myriad of physiological changes ensuing from a changing of the seasons.  Nausea shouldn’t be regarded as a common symptom compared to some of the others.
• Social withdrawal: Seasonal change from fall to winter often promotes social isolation and withdrawal. Many people don’t like the cold conditions, and stay cooped up in their homes for the sake of comfort rather than leaving to socialize with others.  The social withdrawal associated with seasonal affective disorder may exacerbate the depressive symptoms.
• Sleepiness: You may feel sleepier than usual, almost as if you’re stuck in a constant state of somnolence. Seasonal affective disorder can trigger hypersomnia and excessive daytime sleepiness.  This sleepiness is triggered by excess melatonin as a result of insufficient daytime bright light exposure.
• Weight changes: Most people experience weight gain as a result of appetite increases, sedentarism, and a slowed metabolism. Other people that experience reduced appetites or who refuse to eat as a result of their depressed mood may experience varying degrees of weight loss.  Weight changes associated with seasonal depression are considered common.

Note: Those experiencing seasonal affective disorder in the winter may experience different generalized symptoms than those experiencing it during a different season (e.g. summer).

Seasonal Affective Disorder Diagnosis (Criteria)

Seasonal affective disorder is no longer regarded as a “unique disorder” by the DSM (Diagnostic Statistical Manual of Mental Disorders).  Instead it is classified as a “course specifier” and is used to identify a specific subtype of major depressive disorder.  To fit the diagnosis for seasonal affective disorder (SAD) or the “Seasonal Pattern Specifier” a person must meet the following criteria:

1. Person must have depressive episodes at a specific time of year
2. Remissions or mania/hypomania occur at a specific time of year
3. All seasonal depression patterns must have lasted 2+ years with the absence of “non-seasonal” depressive episodes
4. All seasonal depressive episodes must outnumber the depressive episodes occurring throughout a person’s lifetime

It is important to mention that many people experience Subsyndromal Seasonal Affective Disorder.  This is a mild form of seasonal affective disorder in which the symptoms are barely noticeable, but still taking a minor toll on a person’s functioning.  In many cases the person may sense that they feel more depressed or moodier than usual, but it won’t be as obvious as someone with full-blown seasonal affective disorder.

Note: Subsyndromal SAD is thought to affect more than double the amount of people compared to standard SAD.

Seasonal Affective Disorder Treatment

There are many ways to treat seasonal affective disorder. Some of these treatments may be more or less effective than others depending on the season associated with the depression.  Since most cases of seasonal affective disorder are associated with winter months, bright light therapy is universally regarded as the most effective treatment option.

Light therapy: Due to the fact that a lack of bright light is known to disrupt the circadian rhythm and cause depression, using a light box artificially generate bright light can alleviate depressive symptoms.  Light therapy uses a light box formatted to emit significantly more lumens than standardized lights.  Those engaged in light therapy will utilize either: a full-spectrum bright “white” light (10,000 lux), a blue light targeting specific wavelengths (2,500 lux), or blue-green lights (350 lux).

Bright light therapy is considered a highly effective treatment for seasonal affective disorder.  A patient places the light approximately 50 cm in front of their face with eyes open, but not staring directly into the light.  Treatment sessions are typically at least 30 minutes and may be prescribed once or twice per day.  There are disputes regarding whether white light, blue light, or blue-green light is the most effective option.

The idea behind bright light therapy is that it tricks the brain into thinking the sun is up in the sky.  This bright light reduces melatonin during the day and normalizes the body’s circadian rhythm, but typically takes weeks rather than days for optimal results.  Normalization of the circadian rhythm is thought to eradicate seasonal depression for many people.

Dawn simulation: Another effective treatment for seasonal affective disorder is known as “dawn simulation.”  This is a technique that utilizes artificially-timed lights in the bedroom to gradually increase in brightness over a designated time span, just as if the sun were rising.  The simulation can be programmed to range from 30 minutes to 2 hours, mimicking a naturalistic rising of the sun as would occur during summer months.

Think of this as an artificially simulated sunrise.  Your body adapts to the artificial light and triggers a natural awakening.  Some believe that dawn simulation is superior in efficacy to bright light therapy due to the fact that it is more efficient at resetting the circadian rhythm by regulating the sleep-wake cycle.  In particular it is thought that the body is most responsive to signaling in the morning compared to other times throughout the day.

The light used in dawn simulation ranges from 100 lux to 300 lux, which is considerably less than that utilized in bright light therapy (10,000 lux).  In any regard, some people find this intervention just as effective (or more effective) than bright light therapy.

Cognitive behavioral therapy (CBT): Although cognitive-behavioral therapy probably won’t address the root of your seasonal depression, it can be an effective coping intervention.  Cognitive behavioral therapy will help you correct illogical and depressive thinking patterns, while simultaneously changing your behavior.  The combination of thought and behavior change could potentially alleviate some of your depression.

Many studies have found CBT to be equal in efficacy to pharmaceutical antidepressants.  Sometimes having someone to talk to when we’re experiencing seasonal depression also serves as a social contact, making us feel less isolated and withdrawn.  In addition to bright light therapy and dawn simulation, severe cases of seasonal affective disorder should be discussed with a competent psychotherapist.

Physical exercise: A reason that many people become depressed during winter months is related to sedentary habits.  There’s less activities going on when it gets cold out, and the motivation to stay in bed all day, watch TV, or play video games is increased.  Humans are naturally wired to avoid pain, hence the reason they usually stay cooped up inside rather than face the harsh conditions.

There are well-documented psychological benefits of exercise, one of which happens to be the growth of new brain cells (neurogenesis).  To get your neurotransmission properly balanced and to clear out toxins from junk foods you’ve consumed, exercise is necessary even during the winter months.  Some studies have shown that combining exercise with bright light therapy improved mood more than either standalone intervention.

Relocation: Perhaps an obvious solution or cure for seasonal affective disorder is to relocate (move).  This relocation could be temporary (only during the season of your depression) or could be permanent.  You may want to move to a warmer climate that’s closer to the equator for superior sunlight and reduced likelihood of seasonal depression.

Assuming you end up dealing with severe seasonal depression for months of the year, you may want to consider packing up shop and moving to a climate that allows you to stay in a good mood year-round.  Despite the fact that this is an obvious solution, it isn’t often discussed or even considered.

Supplementation: In addition to the aforementioned treatment options, you may also want to optimize your supplementation.  Perhaps a couple of supplements that you may want to consider include: melatonin and vitamin D.  Without sufficient sunlight, it is virtually guaranteed that your vitamin D levels are low – which is suboptimal for general health.

Some evidence has shown that strategic supplementation of melatonin may be beneficial for restoring a disrupted circadian rhythm and/or sleep cycle.  Melatonin is known to have an effect on sleep and mood, acts as a neuroprotective agent, and is considered an important hormone.

Vacation: Another possible treatment strategy to consider would be taking a vacation to a warmer, sunnier climate.  Even a vacation for a week or two gives you plenty of time during the winter months to get some much-needed vitamin D, and sufficient sunlight exposure.  The sunlight exposure and reduced stress associated with a vacation may significantly reduce or fully eradicate depressive symptoms.

Other treatments for seasonal affective disorder (SAD)

Assuming that you’re suffering from seasonal affective disorder, below are some other possible treatment strategies that you may want to consider.  These include: pharmaceutical drugs (e.g. antidepressants), negative air ionization, and tanning beds.

Antidepressants: A common treatment option for seasonal affective disorder is the prescription of an antidepressant.  The problem with this treatment strategy is that the depression is caused by seasonal changes, which possibly triggers a neurochemical imbalance.  The medications prescribed for depression (most often SSRIs) target serotonin, which may or may not help treat seasonal affective disorder.

Even if a medication ends up providing symptomatic relief, people often experience unwanted antidepressant side effects such as sexual dysfunction and weight gain – which may exacerbate depression.  Furthermore, most people don’t realize that antidepressants utilized to treat seasonal depression often are difficult to discontinue with debilitating withdrawal symptoms.  Should you go the pharmaceutical treatment route for your seasonal depression, you may end up with an antidepressant-induced chemical imbalance upon discontinuation.

The most common class of drugs prescribed for seasonal depression include SSRIs and SNRIs.  The atypical antidepressant Wellbutrin (Bupropion) may be the most favorable though due to the fact that it acts as an NDRI, which increases energy.  Other drugs like Provigil for depression in winter months may be suitable off-label interventions due to the fact that they increase energy; some research supports this suggestion.

Negative air ionization: A lesser known intervention for the treatment of seasonal affective disorder is “negative air ionization.”  This method involves the strategic emission of charged particles into a person’s room while they sleep.  It is speculated that negative air ionizing machines simulate summer air, which elicits beneficial effects on a person’s physiology.

It should be noted that if you are using a general air purifier, you probably won’t be getting any antidepressant effect.  This is due to the fact that most general air purifiers do not deliver a substantial dose of negatively charged ions to make any difference in mood.  Some studies have discovered that negative air ionization has significant potential to improve cases of winter depression.

Tanning beds: While tanning beds may not have been investigated as a potential intervention for seasonal affective disorder, they may be worth trying.  Obviously you’ll want to limit your exposure and probably find a UVB “safe” tanning bed.  Exposure can help facilitate the synthesis of vitamin D and give you a healthy tan.

Plus lying in a tanning bed during the winter months may result in the perception of a hot summer sun.  The perception that someone is lying out under the sun, getting a tan, and reaping similar physiological effects as lying in the sun can make a difference.  Although the eyes cannot remain open during tanning, some of the physiological effects of tanning beds could reduce winter depression.

Note: It should be noted that many of these interventions may be effective standalone treatments, but efficacy may be increased when combined with another treatment.  For example, a person may find that using bright light therapy, dawn simulation, and CBT is more effective than any of the treatments when used by themselves.

Risk Factors for Developing Seasonal Affective Disorder

There are several factors that may increase your risk of developing seasonal affective disorder including: age, sex, geographical location, genetics, and whether you have a preexisting mental illness.

• Age: People that are younger often have an increased risk of developing seasonal affective disorder compared to those who are older.  Adults considered “old age” are regarded as less likely to experience the winter blues compared to those of younger ages.  It is unknown as to why younger populations are more prone to seasonal affective disorder.
• Geographical location: Those in regions furthest from the equator are at highest risk for developing seasonal affective disorder.  Individuals who live far north or far south are exposed to less sun during the winter and long days during summer; both of these can disrupt circadian rhythms.  Individuals living in Nordic countries tend to experience greater rates of seasonal affective disorder compared to other locations.  That said, there are notable exceptions such as Iceland in which most residents do not become depressed; this is likely due to genetics.
• Mental illness: Some speculate that having a preexisting mental illness or certain psychological sensitivities may provoke seasonal affective disorder.  While those with major depressive disorder cannot be diagnosed specifically with seasonal affective disorder, a seasonal change may intensify an individual’s preexisting depression.  If you have any mental illness, you may find that certain symptoms become increasingly severe during certain seasons.
• Sex: If you are female, you have a greater likelihood of experiencing seasonal affective disorder compared to male.  Seasonal affective disorder is diagnosed more often in women, and some speculate sex-specific evolutionary traits may be responsible.  That said, some reports have suggested that men diagnosed with seasonal affective disorder may have more debilitating symptoms.

Have you suffered from Seasonal Affective Disorder (SAD)?

If you experience seasonal affective disorder, feel free to share your experience in the comments section below.  Mention the severity of your depression, how many years you’ve dealt with it, where you live, and what you’ve found to be the most effective treatment(s) or intervention(s).  To help others better understand your situation, note the time of year when you notice that your depressive symptoms subside.

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