Seasonal Affective Disorder: Definition, Causes, & Treatments

By Sukhman Rekhi, M.A.
​Reviewed by Tchiki Davis, M.A., Ph.D.

What is Seasonal Affective Disorder? Understand the causes and discover some tips to help you cope as the seasons change.

*This page may include affiliate links; that means we earn from qualifying purchases of products.

Like clockwork, every few months brings a season anew. Whether it’s the falling of leaves and cooler breeze in the autumn and winter, or brighter skies and the longer days of spring and summer, as the days change, our moods may too. Perhaps you notice others around you feeling reinvigorated with the changing seasons, but you catch yourself feeling sad, unable to concentrate, and waiting all day to get back to bed. 

Does this sound like you? If so, you could be experiencing symptoms of Seasonal Affective Disorder. Read on to learn more about what it is, what could be causing it, and what you can do to feel a bit better.
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What Is Seasonal Affective Disorder? (A Definition)

Seasonal Affective Disorder, often known as SAD (an unfortunately apt acronym), is a form of Major Depressive Disorder which appears during certain seasonal patterns (Melrose, 2015). For many of us who experience Seasonal Affective Disorder, we may often be most affected during the fall and winter, when days are shorter and gloomier. With the arrival of spring and summer, however, the symptoms of SAD tend to go away entirely. If you find yourself feeling listless, losing the motivation to complete daily tasks, or sensing a lack of joy in activities that once made you happy during certain months of the year, you are not alone. 

In fact, nearly 10 million Americans struggle with the symptoms of SAD every year (Kurlansik & Ibay, 2012). While the majority of cases of SAD occur during the colder months of the year, summer is not a time for fun in the sun for everyone. It is not unheard of for some people to experience SAD during the spring and summer—a type of depression known as Summer-Seasonal Affective Disorder. Contrary to Winter-Seasonal Affective Disorder, the symptoms of Summer-SAD will typically resolve during early autumn.

Video: What is Seasonal Affective Disorder?

Do you happen to be a visual learner? If so, check out this video for an animated explanation of Seasonal Affective Disorder.

Causes and Risk Factors of Seasonal Affective Disorder

Although Seasonal Affective Disorder is seasonally limited, the effects of the condition may still be exhausting and harmful to our well-being. Before we discuss the symptoms of SAD, let’s talk a little about how SAD is caused so we can understand some of the risk factors associated with it.

Seasonal Affective Disorder Causes ​
Research on Seasonal Affective Disorder remains relatively new, first dating back to Dr. Norman Rosenthal’s work in the 1980s. Thus, the causes of SAD are not entirely clear. However, psychologists theorize that three specific biological and neurological changes, or a combination of all of them, can cause a shift in our psychological and social wellness. I will outline these three possible causes below. 

• A change in serotonin levels. Serotonin is a neurotransmitter, or more simply, a chemical messenger in our brains, that is responsible for stabilizing our moods. Research suggests that the decrease in exposure to sunlight can also reduce serotonin activity in our brains (McMahon et al., 2014). When serotonin levels go down, our brains have a harder time balancing our emotions, which puts us at a greater risk for developing depressive moods. 

 

• An increase in melatonin. Do you catch yourself wanting to sleep in during a rainy day? Or maybe take the day off when the skies are gray to snuggle under the blankets and binge-watch your favorite show on Netflix? A change in melatonin might be causing this. Melatonin is a hormone found in the pineal gland of our brains and plays a role in our level of sleepiness throughout the day. When it’s dark outside, melatonin production increases, making us sleepier (Miller, 2005). The transition to colder temperatures and shorter days can influence melatonin levels to increase, which is why fatigue and lethargy are often associated with SAD. 

 

• Disruption of the circadian rhythm. Our circadian rhythm, or our biological clock, is our body’s natural process of monitoring our sleep-wake cycle. As the season changes into winter, the nights become longer, which affects the balance of our sleep-wake cycle. This disruption is further influenced by a change in our serotonin and melatonin levels, which can delay our sleep patterns and alter our daily routines (Lewy et al., 2009). Such a change may make it more difficult to regulate our moods, leading to feelings of depression.

Risk Factors for Seasonal Affective Disorder
While anyone can experience Seasonal Affective Disorder, like most other conditions, some of us may be more likely to experience symptoms of SAD. In summary, females and younger people have an increased risk of developing symptoms of SAD. Below you will find a more detailed overview of risk factors.

• Sex differences. Female-identifying folks tend to be impacted by SAD nearly four times more than their male counterparts (Kurlansik & Ibay, 2012). 

 

• Age. Young adults, typically between the ages of 18-30, have an increased likelihood of displaying symptoms of SAD (Galima, Vogel, & Kowalski, 2020). 

 

• Family History. If you have a parent, grandparent, or other close relatives who have previously experienced SAD, or other depressive disorders, you may have a higher predisposition of experiencing SAD (Galima, Vogel, & Kowalski, 2020).  

 

• Geographic Location. Interestingly enough, where you live can impact your likelihood of developing Winter-Seasonal Affective Disorder. If you happen to call tropical islands and countries close to the equator your home, you likely have the advantage of a lower risk of developing SAD symptoms. However, if you live in the hustling and bustling cities of the American Northeast or are used to shoveling several inches of snowfall from your driveway each year, you most likely live further from the equator. And the latitudinal position of your home determines your exposure to sunlight (Galima, Vogel, & Kowalski, 2020). So, those of us that live further North or South of the equator may want to keep an eye out for SAD symptoms, especially during the winter months.​​

Seasonal Affective Disorder Symptoms

Perhaps you have read this far and are intrigued to understand whether you are showing signs of Seasonal Affective Disorder. Or, maybe, you have noticed someone close to you experiencing a few of these symptoms and want to learn how you can be a support system to them. Let’s first take a look at some telltale signs of SAD before we learn some tips on how to manage it. 

Whether you are someone (or know someone) whose psychological wellbeing is negatively affected in the winter or summer, several of the symptoms of SAD are similar regardless of when your onset of SAD occurs (Melrose, 2015). Below you will find a list of these signs.

• Persistent sadness. This type of sadness is not momentary or temporarily triggered by your favorite character dying in a movie (but of course, we all know the pain and tears that can come with this situation). Persistent sadness may include feeling hopeless, unenergetic, and be accompanied with crying, for most of the day and occurring almost every day. This type of mood typically lasts longer than two weeks. 

 

• Changes in energy levels and interests. Maybe you’re a big sports fan like me, and suddenly find no joy in watching your team play, or you love to read and somehow don’t have the energy to pick up a book off of your bedside table anymore. SAD might be influencing these changes. When you begin to lose interest in activities you enjoy or are having a harder time crossing off the tasks on your to-do list, you may want to reflect on whether your body and wellbeing are affected by the changing seasons. 

 

• Altered sleep patterns. Remember our conversation about melatonin and circadian rhythms? Here’s the effect of those changes. Those of us experiencing SAD may find ourselves sleeping more than normal or having trouble sleeping altogether.

 

• Shifts in behavior. When our moods, sleep, and energy levels change, they may have an effect on our behaviors, too. Some common changes in behavior may include difficulty concentrating, increased irritability, and removing yourself from social situations. 

As we now know, Seasonal Affective Disorder can have a winter or summer onset. While the symptoms listed above tend to develop no matter what season of the year you experience SAD, there are some distinct differences that are worthy of taking into account. 

Winter-Seasonal Affective Disorder Symptoms​

• Sleeping more than normal
• Craving foods high in sugar and carbohydrates (e.g., wanting to eat the whole pumpkin pie rather than a slice (or two) during a holiday dinner)
• Gaining weight due to an increased appetite 

Summer-Seasonal Affective Disorder Symptoms

• Insomnia, or difficulty sleeping at night 
• A reduction in food intake or skipping meals altogether 
• Losing weight due to a decreased appetite 

Seasonal Affective Disorder Treatment and Therapies

If you’re reading this and believe you may be struggling with Seasonal Affective Disorder, the good news is that you don’t have to wait several months to start feeling better. While symptoms of SAD often resolve on their own when the seasons change, we have the power to make things better for ourselves now, whether that is participating in self-help methods or asking for support from medical and psychological professionals. Let’s take a closer look at what some treatments for SAD look like. 

Research has shown a few options for treatment for SAD. These approaches include psychotherapy, medication, and light therapy—and sometimes, a combination of all three of these techniques (Kurlansik & Ibay, 2012).  

Psychotherapy for Seasonal Affective Disorder
Psychotherapy, otherwise known as talk therapy, is exactly what it sounds like. It may not be identical to how TV characters lay on the big couches in their therapist’s office explaining to them their life dilemmas in detail, but talking about problems and emotions to a therapist can look similar. Seeking out help from a therapist may not always be the easiest step for us, but psychological professionals are trained in various therapy styles that can help aid us in our journeys to recovery and better holistic wellness when dealing with SAD. 

One of the most common therapy techniques psychologists use is Cognitive-Behavioral Therapy (Melrose, 2015). Cognitive means relating to thoughts, while behavioral refers to actions. Simply put, cognitive-behavioral therapy focuses on how we can change negative thoughts and behaviors to positive ones, therefore elevating our mood. 

Cognitive-Behavioral Therapy for Seasonal Affective Disorder
But what exactly does this look like in practice? Let’s say you experience SAD symptoms during the wintertime and you hate the thought of tolerating cold weather. When you look at the snow falling outside, you feel upset that you are unable to go on your morning walk with your dog and smell the fresh air while soaking in the sun on your skin. The lack of physical activity and quality time spent with your fur baby is making you feel irritable. 

A therapist practicing a cognitive-behavioral technique might ask you what alternatives might help you conquer this challenge. Maybe you grab a big coat for yourself (and a sweater for your dog) and make snow angels in the front yard. Perhaps you plan a quick and easy getaway to a slightly sunnier location. Or instead, maybe you come up with a list of exercises you can do in the comfort of your own home that elevate your heart, and similarly, your mood. 

Cognitive-behavioral therapy allows you to speak to a professional to recognize the harmful thought patterns that may be occurring and collaborate together to find actionable ways to change negative behaviors into more meaningful and positive ones. 

Medication for Seasonal Affective Disorder

An additional treatment option that may be of benefit to those of us struggling with SAD is medication. More specifically, Selective Serotonin Reuptake Inhibitors, also called SSRIs, are a type of antidepressant medication shown to increase serotonin levels in SAD patients (Partonent & Lönnqvist, 1998). 

As we know, a dip in serotonin in our brains can lead to the destabilization of our moods. The antidepressant medication works to reverse this effect, thus allowing our brains more control in emotion (or mood) regulation. 

It is important to note here that like any other medication, it is recommended to ask your doctor for medications that are best for you and your body. Sometimes, antidepressants can present side effects such as nausea, changes in bowel movement, an upset stomach, and anxiety. When considering medication as a primary option or supplement for your treatment with SAD, it may be a good idea to speak to a healthcare provider about any questions or concerns you may have prior to beginning treatment.

Light Therapy for Seasonal Affective Disorder

Lastly, and certainly not the least, light therapy is a primary treatment option for alleviating symptoms of SAD (Rosenthal et al., 1984). Unlike psychotherapy and medication which require professional support, light therapy is a self-help technique that can support our wellbeing when experiencing symptoms of SAD. 

You may be wondering how light therapy works, especially during the wintertime when light isn’t exactly abundant in supply. Light therapy, also known as phototherapy, is operated through a light box. Yes, you read that correctly—it is indeed a box of special light while eliminating harmful ultraviolet rays, to mimic natural daylight. 

The process of light therapy is relatively simple once you receive a light therapy box from a medical provider or purchase your own. Research suggests that those of us who struggle with Winter-Seasonal Affective Disorder, in particular, turn on our light box first thing in the morning and sit in front of it for 20-60 minutes every day. 

Whether you are getting ready for work, making your breakfast, or taking a few moments to practice some meditation, having a light box in front of you may improve your mood. What does this box do to your brain, you ask? Light therapy has shown success in reducing your melatonin production while increasing your serotonin level. In simple terms, light boxes may aid in making you a little less tired and a bit more inspired, while turning your feelings of sadness into feelings of gladness. 

Light therapy may also include some side effects, such as eyestrain, headaches, and difficulty sleeping. For those of us who may have a diagnosis for Bipolar Disorder, in particular, it is recommended to discuss light therapy options with your medical provider, as this technique may interfere with treatment for Bipolar Disorder.

Video: Light Therapy for Seasonal Affective Disorder

Interested in learning a bit more about light therapy? Check out this video which further explains the use of light therapy in appeasing symptoms of SAD. 

Tips on Managing and Reversing Seasonal Affective Disorder

Treatments may take some time to get used to, but other coping strategies can help us prepare for dealing with Seasonal Affective Disorder, regardless if our onset happens in the winter or summer. 

• Keep your diet in check. Whether it’s cold outside and we’re reaching for a warm midnight snack, or we’re losing the motivation to make a meal when it’s too bright out, having a balanced diet can help us manage symptoms of SAD better. In the wintertime, we experience a reduction of Vitamin D due to a lack of sunlight (Melrose, 2015). Some foods that can help us combat this include eggs, salmon, and fruits and vegetables, such as oranges or leafy greens. Don’t seem to have the energy to make a meal? It might help to ask a friend, family member, or partner to cook a healthy snack together. Not only can this help you feel properly satiated, but you may even benefit from some social support from a loved one.

 

• Try to stay active. Sometimes the weather outside may be in freezing temperatures. Other times, there’s not enough air conditioning to keep you from sweating out the heatwave. It may not always be the best day to go outside, but we still have some options to stay active inside. Whether you have a gym membership or put on your favorite yoga video on YouTube, getting your body moving can alleviate lethargy and sadness caused by SAD thanks to the endorphins you release when you exercise. And hey, if the weather isn’t so bad and you have a few moments to step out, a nice stroll in the park or quick run may also help. 

 

• Invite in social support. If you’re anything like me and feel thrilled with the opportunity to spend time with people, prioritizing social support may help elevate negative emotions or thoughts that you may have. Whether it’s meeting a friend for coffee, having a movie night with your family, or even FaceTiming a loved one to chat, social support not only lifts our spirits but can make us feel less alone when dealing with depressive moods. ​

Articles Related to Seasonal Affective Disorder

​Want to learn more? Check out these articles:

• Feeling Sad? Try These 20 Science-Based Depression Busters
• Emotion: Definition, Theories, & Examples
• Emotional Dysregulation: Definition, Examples, And Tips
• ​Mood Disorders: Definitions, Symptoms, & List
• ​Blue Light: Effects on Sleep & Health
  

Books Related to Seasonal Affective Disorder

If you’d like to keep learning more, here are a few books that you might be interested in.

• ​​Winter Blues, Fourth Edition: Everything You Need to Know to Beat Seasonal Affective Disorder
• Positive Options for Seasonal Affective Disorder (SAD): Self-Help and Treatment
• ​Sadness, Love, Openness: The Buddhist Path of Joy

Final Thoughts on Seasonal Affective Disorder

When the seasons begin to change and you notice that you also feel a little different, perhaps you find yourself experiencing symptoms of Seasonal Affective Disorder. Hopefully, this article supported your understanding of the causes, symptoms, and treatments for SAD. While this condition can make us feel hopeless, tired, and isolated, I hope you realize that you are not alone. Whether it’s asking for professional help, relying on your loved ones, or even sticking to small healthy habits that lift your mood, nurturing our bodies and well-being even on the dark days can help bring us some light. 

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References

• Galima, S. V., Vogel, S. R., & Kowalski, A. W. (2020). Seasonal affective disorder: Common questions and answers. American family physician, 102(11), 668-672.
• Kurlansik, S. L., & Ibay, A. D. (2012). Seasonal affective disorder. American family physician, 86(11), 1037-1041.
• Lewy, A. J., Emens, J. S., Songer, J. B., Sims, N., Laurie, A. L., Fiala, S. C., & Buti, A. (2009). Winter depression: integrating mood, circadian rhythms, and the sleep/wake and light/dark cycles into a bio-psycho-social-environmental model. Sleep medicine clinics, 4(2), 285-299.
• McMahon, B., Andersen, S. B., Madsen, M. K., Hjordt, L. V., Hageman, I., Dam, H., ... & Knudsen, G. M. (2014). P. 1. i. 037 Patients with seasonal affective disorder show seasonal fluctuations in their cerebral serotonin transporter binding. European Neuropsychopharmacology, (24), S319.
• Melrose, S. (2015). Seasonal affective disorder: an overview of assessment and treatment approaches. Depression research and treatment, 2015.
• ​​Miller, A. L. (2005). Epidemiology, etiology, and natural treatment of seasonal affective disorder. Alternative medicine review, 10(1). 
• Partonen, T., & Lönnqvist, J. (1998). Seasonal affective disorder. CNS drugs, 9(3), 203-212.
• Rosenthal, N. E., Sack, D. A., Gillin, J. C., Lewy, A. J., Goodwin, F. K., Davenport, Y., ... & Wehr, T. A. (1984). Seasonal affective disorder: a description of the syndrome and preliminary findings with light therapy. Archives of general psychiatry, 41(1), 72-80. ​

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