Health and Disease

SAD: Depression Influenced by the Seasons

Depression is an enigma of a disorder, with many unclear causes. One surprising source behind a certain type of depression is the changing of seasons throughout the year; such an unexpected phenomenon is more common than one would think.


Depression is a disorder notoriously known for its ambiguity. It can develop in an individual at any age, from sprouting teenagers to middle-aged adults. Furthermore, there is a plethora of both long and short-term causes of depression that can amalgamate over time and contribute toward the depressive disorder. These causes can stem from hereditary, psychological, and environmental aspects in one’s life, as well as a number of other areas. When thought of, the causes of depression often regard specific cases of each patient’s individual life: instances of trauma, underlying illnesses, etc. However, this is not true for one type of depressive order in particular: seasonal affective disorder (SAD).

What is SAD?

Seasonal affective disorder is a type of depression stemming from more general environmental changes. Specifically, it is linked to the change in seasons throughout the year. The disorder will begin when a certain season begins and end when another season comes around, at about the same times every year. SAD commonly occurs when the winter season comes, and is therefore called winter depression, in which changes occur during the winter months and cease when the spring/summertime comes around. Though less frequent, summer depression can also be a possibility in individuals, which is when the disorder starts in the spring or summer and dissipates in the late fall and winter. In these seasonal periods of depression, people experience drastic shifts in behaviors and moods, up to the point where it disrupts normal thoughts and daily activities. The severity of such changes can differentiate from a minor mood swing to a true depressive disorder. 


Overall, SAD has many common symptoms. A major indicator is strong feelings of depression for the majority of the day, everyday. Furthermore, very clear and sudden shifts in established behaviors, like a loss of interest in activities that were once enjoyed, a lack of energy, and a lack of sleep, frequently occurs. Self-deprecating and suicidal thoughts, sluggish actions, and even physical changes regarding weight also point toward a depressive disorder. While these can be indicators of any general depressive disorder, the occurrence of the changes at only a certain time in the year during specific seasons points toward a development of SAD. 

There are several symptoms that are seen more with winter depression. Examples include oversleeping, weight gain, and decreased energy. Conversely, summer depression is associated with lack of sleep, weight loss, and increased anxiety.

Sometimes, some of these symptoms can be normal, temporary mood swings. However, if they persist for an extended duration, it is important to note such behaviors and recount them to a doctor for a diagnosis.


The inducing of SAD is the change in seasons. But what exactly does the seasonal change do to an individual to bring about such drastic effects? Research has suggested that it was mainly the changes in sunlight levels in the winter seasons. Sunlight usually controls the amount of serotonin in the body: a neurotransmitter associated with mood regulation. People with SAD may have poorer serotonin function around certain light levels, and thus have a decreased mood regulation with lower levels of light. Furthermore, the hormone melatonin can also play a role behind SAD symptoms. Melatonin regulates sleep, and research findings have shown that people with SAD can overproduce the hormone, causing oversleeping during summer depression. Overall, chemical disruption in the body, especially those that affect core aspects such as mood and sleep, can certainly push a depressive state. 

The development and effects of SAD can be amplified by other factors as well. Primarily, individuals who have family members with SAD or other types of depression can be susceptible to a higher likelihood of SAD development. Also, SAD may be more common in an individual who already has a pre-existing major depressive or bipolar disorder.

An individual’s location in relation to the equator can also affect the development of SAD. It is more common in those who live farther north or south from the equator, as there are longer summer days and darker winter days.

SAD also occurs more in women than men. Millions of people in America may suffer from the disorder without truly knowing; some people consider such actions as signs of “laziness” rather than true depression. 


There are several methods that can be utilized in the treatment of SAD. Since the most common form of SAD is winter depression, which is usually due to changes in sunlight, light therapy can be used as treatment. There are several variations of light treatment, some involving a very bright box or a light visor that is worn like a cap on one’s head. The patient will either be exposed to the box or wear the cap for about 30-45 minutes a day during the time periods of depression, usually in the morning. These lights are about 20 times brighter than a regular indoor light, and also filter out damaging UV rays to prevent serious eye damage. Overall, it is a helpful method to provide balance to the chemicals that are affected by the winter’s lack of light. Some side effects include eye strain, sleeping problems, headaches, and fatigue.

Another form of treatment is medication. Antidepressants called serotonin re-uptake inhibitors (SSRIs) can improve the moods of patients, and can manage the serotonin disruption during winter depression by increasing serotonin levels. Another medication called bupropion can prevent seasonal depressive symptoms when taken daily. These medications can have different side effects depending on the individual.

Brian Caballo, Youth Medical Journal 2020



By Brian Caballo

Brian Caballo is a student at The Bronx High School of Science in New York City, NY. He is mainly interested in the fields of neuroscience and stem cell biology.

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