Seasonal Affective Disorder: Current Insights and Therapies

Seasonal Affective Disorder (SAD) is a psychological disease that more commonly occurs in the winter. It is categorized as a form of depression that is identified based on the season and on the frequency of the disease. The symptoms more commonly take place during the fall and winter seasons when there is an overall lack of light, sunlight or otherwise and the most common months are usually January and February. However, there have been reported cases in the summer, although they tend to be less frequent [1,2]. 

This disease tends to be ignored, and casually written off as just being “sad” or “not feeling well.” It however can impact not only a patient’s mood, but his/her daily performance and function. Up to 5 percent of adults in the U.S. experience SAD lasting up to 40 percent of the year, and it is found to be more common to appear in women than men. This disease is more frequent in those who live a great distance from the equator, leading to less total sunlight in the winter. SAD has been shown to be caused by a chemical imbalance in the brain signaled by shorter daylight spans and less overall periods of sunlight in the winter. With the changing seasons, the affected patients can experience a vast shift in their internal circadian rhythm that can cause a delay or upset of their daily schedule [3,4]. Although the working mechanisms and etiology of SAD are not clear, advances in neuroscience revealed that hypothalamic neuropeptides such as hypocretin and orexin play a key role in sleep-wakefulness cycle, and demonstrate seasonal variations suggesting a link to SAD [5,6].

SAD is regarded as a category of depression that is uniquely recognized by its repeating seasonal occurrences, with symptoms that lasting up to 3-5 months each year. Furthermore, the symptoms and patterns of SAD also strongly correlate with those of clinical depression, and some specific symptoms only caused by the disease itself during both its summer and winter occurrences. Though not all symptoms may occur in the same patient, some could include: a depression that reoccurs for most of the day; losing interest in things you usually enjoy; drastic changes in eating habits or weight; difficulties with sleeping; difficulties with concentrating; and having chronic feelings and thoughts of suicide and death [7,8]. 

In the winter occurrences of SAD, other specific symptoms can include extreme oversleeping; overeating or binging; massive increases in weight; and episodes of social removal. Specific symptoms of the summer occurrences of SAD are similar and can include trouble in sleeping; a loss in the urge to eat; increasing mood shifts of agitation and anger; intense anxiety; and periods of violence urges or tendencies [8].

Patients with SAD are usually afflicted with symptoms of clinical depression or the symptoms described above. The episodes are usually in effect in specific seasons, like the winter or summer periods, for at least two successive years. In the American Family Physician Journal, if the disorder is suspected, a full evaluation using current DSM-IV-TR depression principles is required. It is necessary for the existence of the disorder to be confirmed before treatment can be established [8].

SAD can be effectively treated by multiple modalities including light therapy, antidepressant medications, talk therapy, or a combination of these treatments. Even though the symptoms disappear with the transitions of the season, they can comparatively rapidly improve with treatment. A very common form of treatment is light therapy, which involves exposing the patient to a light-emitting box that emits a bright high-frequency light that filters out dangerous Ultraviolet (UV) rays. It is usually a requirement for this treatment to be conducted for 20 minutes a day, and effects usually start to take affect within one to two weeks of the initial treatment. To maintain these benefits, treatment is usually retained through the affected season, and can be started in the early stages of each season to prevent any expected symptoms. Light therapy can require sitting in front of the box for up to 30 minutes, usually soon after the patient has woken up [9]. 

Despite its effectiveness, light therapy may not work for everyone. Some patients may need a stronger, brighter, and more focused light. Though some may not be able to handle the bright light, and the light may cause other symptoms to appear, and worsen the disease. Additionally, there is a risk of eye damage, although low in incidence. Therefore, any patient with pre-existing conditions of diabetes or eye disease should be evaluated before undergoing light therapy [10]. 

Another major modality is Cognitive Behavior Therapy (CBT). CBT is used to help patients learn how to deal with difficult situations and has also been adapted to practically help people with SAD. It is initiated in two weekly group sessions for up to 6 weeks and is concentrated on substituting positive thoughts in the patient instead of darker, or symptominitiating thoughts about winter season. Furthermore, the process of behavioral activation, which assists the patient in recognizing and engaging in the more favored indoor and outside activities, to help treat the loss of interest that occurs in the wintertime. In multiple studies, both light therapy and CBT were found to be successful in the treatment of SAD, but with some symptoms treated faster and more efficiently with light therapy. On the other hand, another study found that the positive effects of CBT treatment lasted longer with consecutive treatments over time [11,12]. 

Moreover, pharmacological therapy with antidepressants such as Selective Serotonin reuptake Inhibitors (SSRIs) is the last pillar of SAD treatment. These antidepressants are used to limit surges in serotonin activity and are mainly used to treat SAD when symptoms occur. This medication can improve patients’ moods and feelings, and most used SSRIs include fluoxetine, citalopram, sertraline, paroxetine, and escitalopram. Bupropion, an FDA-approved drug, can prevent reappearance of extreme episodes of depression when it is taken daily from the fall to the start of the next spring [13-15]. 

Lastly, it has been found in several patients with SAD that they have a lack of vitamin D, and supplements of Vitamin D may help to diminish and improve their symptoms. Nevertheless, studies around this possible treatment have shown mixed findings, with some producing that it is as successful as light therapy, and others ending with the treatment having no effect. Similarly, an increase in exposure to sunlight and bright has been found to help with symptoms of SAD, which can include spending time outside in the day or getting sunlight in the patients’ room or office. Physical wellness has also been proven to help, such as: exercise, healthy and steady eating, maintain a proper sleep schedule, and staying involved and in touch with family or friends [16].