US Pharm. 2024;49(5):8-12.

Seasonal affective disorder (SAD), also referred to as winter blues, represents one of the most prevalent and complicated psychiatric disorders faced by patients today. Approximately 10% of adults in the United States experience SAD, typically enduring it about 40% of the year. The prevalent pattern involves experiencing depression during fall/winter, followed by a period of remission in spring/summer. This mental health issue—often overlooked and insufficiently addressed—falls under the subtypes of major depressive disorder (MDD) and bipolar disorder (BPD). MDD usually manifests as prolonged periods of intense low mood alongside diminished motivation and interest, whereas BPD fluctuates between depressive episodes and those marked by heightened energy and hyperactivity. Winter-pattern SAD, which constitutes a significant portion of cases, tends to resemble MDD symptoms more closely. SAD, along with other depressive disorders, poses a considerable public health threat in the U.S., as evidenced by an estimated 1.7 million suicide attempts in 2021 and a 2.6% rise in suicide-related deaths from 2021 to 2022.1-4

The effects of SAD reach far beyond individual suffering, imposing significant societal and economic challenges. SAD can hinder cognitive ability, diminish productivity, and strain interpersonal connections, resulting in a lower quality of life for those affected. Left untreated, SAD may worsen existing mental health issues and heighten the risk of concomitant conditions, such as anxiety disorders and substance abuse. The societal ramifications of SAD are exacerbated by absenteeism from work or school, increased healthcare utilization, and elevated healthcare expenses. Moreover, SAD’s nature perpetuates cyclical patterns of impairment, placing a cumulative burden on affected individuals and healthcare systems alike. Addressing the impact of SAD requires comprehensive strategies incorporating preventive measures, prompt diagnosis, and evidence-based treatments to alleviate its societal and economic toll and enhance overall well-being.5


The exact cause of SAD remains unclear, but several theories have been proposed to explain its development. One theory suggests that disruptions in an individual’s internal clock, known as circadian rhythm, play a role. Longer winter nights may lead to excessive production of melatonin—a hormone that signals sleepiness—contributing to feelings of drowsiness and lethargy during the winter months. Another related theory, the phase shift hypothesis, suggests that seasonal changes disrupt the timing of our circadian rhythm, affecting various bodily processes like melatonin production and body temperature regulation, potentially leading to winter blues symptoms.2,6-9

Additionally, individuals with SAD may have a problem with how sensitive their retinas are to light. Normally, retinas become more sensitive to light during the winter to adjust for shorter days, but in people with SAD, this response may be diminished, causing disruptions in his or her circadian rhythm. Studies have found that some SAD patients have retinal abnormalities, and light therapy has been shown to improve this sensitivity issue.10

Furthermore, individuals with winter depression often show increased activity of the serotonin transporter—a molecule responsible for removing serotonin (a neurotransmitter important for mood regulation) from circulation. This heightened activity can lead to lower serotonin levels. Reduced exposure to sunlight during winter may also decrease vitamin D production, which influences serotonin activity. Vitamin D deficiency has been linked to significant depressive symptoms, highlighting the complex interaction between environmental factors, neurotransmitters, and SAD.9,11

Genetic predisposition also plays a significant role in SAD. Individuals with a history of depression or family members with SAD are at a higher risk of developing the disorder. Additionally, age and gender are important factors, with females being four times more likely than males to experience SAD. SAD typically begins between the ages of 18 and 30 years and becomes more prevalent with age.2,9


Symptoms of winter seasonal pattern disorders primarily include feelings of sadness and low energy. Individuals with SAD may also exhibit irritability, frequent crying, fatigue, lethargy, difficulty concentrating, increased sleep, decreased activity levels, social withdrawal, cravings for carbohydrates and sugars, and weight gain due to overeating. In contrast, symptoms of the less common summer seasonal pattern disorder typically involve poor appetite  leading to weight loss, insomnia, agitation, restlessness, anxiety, occasional episodes of violent behavior, and irritability.9

It is important to understand that the severity of seasonal pattern disorders varies among individuals. While some may only experience a milder form known as subsyndromal S-SAD, others may be severely incapacitated and unable to function normally. SAD is distinguished from nonseasonal depression by the characteristic timing of onset and remission of depressive episodes (fall-winter or spring-summer). Unlike nonseasonal depression, there is a temporal relationship between the recurrence or remission of depressive episodes in SAD. If patients present with severe depressive symptoms, including thoughts of suicide, it is crucial to refer them to their physicians for appropriate treatment promptly.9


Treatment guidelines for SAD typically advocate for a multifaceted approach, incorporating both pharmacologic and nonpharmacologic interventions to enhance mental and physical well-being in affected individuals. These interventions encompass light therapy, antidepressants, psychotherapy, and lifestyle adjustments.

Light Therapy

Light therapy, also known as bright light therapy or phototherapy, is considered the least invasive, most natural, and most extensively studied treatment for SAD. This therapeutic approach involves exposing individuals to bright artificial light with intensities typically ranging from 2,500 to 10,000 lux. Light therapy devices, often marketed as “light boxes,” are commercially available. These devices disperse light while filtering out harmful ultraviolet rays. The underlying mechanism of light therapy centers on diminishing elevated levels of melatonin in the bloodstream, commonly observed in individuals with SAD due to reduced exposure to natural light. Additionally, light therapy is believed to normalize phase-shift delays, thereby contributing to its therapeutic effects.8,9,12

Counseling patients to use a light box upon waking in the morning, starting from early fall until spring, has demonstrated efficacy in alleviating SAD symptoms. Typically, patients position themselves 12 to 18 inches away from the light source for 30 minutes daily in the morning. Improvement in symptoms is often noticeable after 1 to 2 weeks of consistent therapy. Treatment is typically recommended to continue until remission is achieved in the spring or summer months, as discontinuation of light therapy may lead to symptom recurrence. Adverse effects associated with light therapy, such as blurred vision, eye strain, or headache, are generally mild and transient, although they should be monitored closely.9,12,13

An alternative to traditional light therapy is dawn simulation, which employs a much weaker light (e.g., 250 lux) gradually applied at the end of  patients’ sleep cycle and as they awaken. This approach offers an alternative option for individuals who may not tolerate the intensity of traditional light therapy or prefer a gentler treatment method.12,14


The use of second-generation antidepressants, such as fluoxetine, paroxetine, sertraline, and bupropion, has shown effectiveness in treating SAD (see TABLE 1). While light therapy has traditionally been the first-line treatment for SAD, there are circumstances when antidepressants may be considered as the initial choice. Individuals with SAD must collaborate closely with their healthcare providers to devise a personalized treatment plan tailored to their specific needs, symptom severity, and preferences. However, it is important to be aware of the potential side effects associated with antidepressant therapy, including nausea, vomiting, headache, nervousness, anxiety, heart palpitations, and an increased risk of suicidal ideation, particularly in teens and young adults when initiating antidepressants. Although there is some evidence supporting the use of second-generation antidepressants for SAD, a Cochrane review has highlighted insufficient evidence to draw overall conclusions regarding their efficacy. Therefore, antidepressants may be considered for patients whose symptoms significantly impair social or occupational functioning, but their use should be carefully monitored and weighed against potential risks and benefits.9,12,15,16


Psychotherapy, particularly cognitive-behavioral therapy (CBT), can help individuals develop coping strategies to manage symptoms and identify negative thought patterns associated with the disorder. CBT may also include behavioral activation techniques to increase engagement in rewarding activities and social interactions, which can alleviate depressive symptoms. By promoting cognitive restructuring and behavioral activation, CBT equips patients with coping skills to manage SAD symptoms and prevent relapse.9,12

Self-Care Management

St. John’s wort (hypericum extract) has shown effectiveness in treating symptoms of SAD. Research indicates that hypericum alone can effectively alleviate SAD symptoms, although combining it with light therapy may offer slightly enhanced benefits. Hypericum both alone and in combination with light therapy has demonstrated significant improvements in depressive symptoms, including anxiety, loss of libido, and insomnia. However, it is essential to consider individual medical history and medication lists before recommending St. John’s wort, as it can interact with several medications.8,17,18

Melatonin supplementation has also been explored as a treatment option for SAD. Studies have shown that administering exogenous melatonin, particularly in controlled-release formulations, can improve sleep quality and vitality in SAD patients. Melatonin, taken at bedtime, may contribute to mood regulation and provide another option for individuals suffering from SAD.19

Additionally, low levels of vitamin D have been associated with SAD, as vitamin D plays a role in serotonin regulation in the brain. Since sunlight exposure is a primary source of vitamin D, supplementation may be beneficial, especially during the darker winter months when natural sunlight is limited. While further research is needed to confirm this relationship, individuals can consider taking vitamin D supplements before the onset of winter darkness to potentially prevent depressive symptoms.20,21

For individuals who are experiencing mild-to-moderate depressive symptoms associated with SAD, various lifestyle interventions can significantly improve their condition. Counsel patients that diet, exercise, stress management, social engagement, and outdoor exposure can all contribute to alleviating depressive symptoms. Healthy sleep hygiene and exercise routines are especially recommended throughout treatment. Sleep hygiene involves creating a regular sleep-wake cycle. Patients should establish a consistent bedtime each night, ensure that their sleep environment is comfortable, and avoid consuming heavy meals or fluids close to bedtime. As mentioned earlier, SAD may be caused by delayed circadian rhythms, which can initially cause insomnia. To improve sleep and regulate circadian rhythms, patients are advised to minimize light exposure in the 2 hours before sleep onset. This includes light boxes, bright rooms, and blue light emitted from electronic devices such as computers, televisions, and cellular phones.22,23

Daily walks outside—even on cloudy days—can significantly improve SAD symptoms, especially when combined with light therapy. A study showed that patients who took daily walks for 60 minutes each morning alongside light therapy had greater improvement in symptoms than those who only received light therapy. Aerobic exercise, such as biking, running, and swimming, has also been proven helpful in managing SAD. A study found that regular aerobic exercise led to greater improvement in depression symptoms than no exercise or relaxation exercises. Informing patients to exercise at least three times a week for 1 hour is another way to help them overcome SAD symptoms.22,24-26


Pharmacists play a crucial role in supporting individuals with SAD. Pharmacists’ accessibility allows them to raise awareness and educate patients about the signs, symptoms, and treatment options for this mood disorder. Pharmacists can advise on first-line options like light therapy. They can also offer guidance on complementary strategies such as maintaining a healthy sleep schedule, regular exercise, and incorporating mood-boosting foods into the diet.

For patients prescribed antidepressants, pharmacists can ensure that patients understand how to take their prescribed medications, potential side effects, and interactions with other drugs. They can monitor medication adherence and can make recommendations for dose adjustments as needed, minimizing risks and optimizing therapeutic outcomes.

Beyond initial treatment, pharmacists act as vital resources. They can monitor medication adherence, identify potential issues, and answer a patient’s questions throughout his or her treatment plan. Developing a personalized approach that addresses low motivation or lack of understanding can significantly improve adherence.

Furthermore, pharmacists can offer a supportive and empathetic environment for patients with SAD. Being someone to talk to and offering encouragement can make a big difference. They can provide support and education, but if a patient presents with severe symptoms like suicidal thoughts, pharmacists can make crucial referrals to doctors or therapists within their healthcare team. Through education, treatment management, ongoing support, and potential referrals, pharmacists play an active role in helping patients with SAD manage their symptoms and improve their overall well-being.


SAD is a complex and undertreated psychiatric condition that can significantly impact individuals who experience symptoms. SAD often gets overshadowed by its overarching categorization of MDD or BPD, but its seasonal onset underscores the importance of proactive management and tailored treatment. SAD presents various treatment options, ranging from nonpharmacologic to pharmacologic interventions, mainly aimed at alleviating symptoms of depression. The pharmacist’s pivotal role in educating, guiding, and supporting patients cannot be overstated. By acknowledging awareness, facilitating access to resources, and promoting adherence to treatment regimens, pharmacists can help patients make crucial decisions in improving their mental health outcomes. As researchers and healthcare professionals strive to understand this disorder better, collaborative efforts across healthcare disciplines are essential in mitigating its burdens and creating a more supportive environment for individuals navigating the challenges of SAD.

What Causes SAD?

The exact cause of SAD is unknown, but several factors are thought to play a role. One large factor is the change in sunlight, especially during fall and winter. Less sunlight can mess up your body’s internal clock, called the circadian rhythm, which affects how much serotonin you have. Serotonin is a chemical in your brain that affects your mood. Sunlight also helps your body make vitamin D, which helps regulate your mood. Another hormone called melatonin, which helps you sleep, might also be affected by the change in daylight hours and could worsen SAD symptoms.

What Are the Symptoms of SAD?

Symptoms of SAD closely resemble those of depression and can include feelings of sadness, anxiety, irritability, fatigue, changes in sleep patterns, and even suicidal thoughts. Winter pattern SAD may involve oversleeping and weight gain, while summer pattern SAD may lead to insomnia and weight loss. Talk to your doctor if you experience these symptoms, especially during fall and winter. Your doctor can help you get a diagnosis and create the right treatment plan for you.

Am I at Risk for SAD?

Several factors can increase the risk of developing SAD, including a history of depression, family history of SAD, age, gender, and environmental factors. Lifestyle choices and stress levels can also contribute to SAD risk.

How Is SAD Treated?

While SAD does not have a cure, there are many ways to manage its symptoms. Treatments may include light therapy, counseling, medication, and lifestyle changes. Try to spend time outdoors, even when it is cloudy, as natural light can help. Aim for about 30 minutes of exercise most days of the week—it is great for boosting your mood! Keep a regular sleep schedule, even on weekends, to help regulate your body’s internal clock. Eating plenty of fruits, veggies, and whole grains can fuel your body and help improve your mood. Find healthy ways to cope with stress, like yoga, meditation, or spending time in nature. Do not forget to stay connected with loved ones and engage in social activities. And most importantly, do not hesitate to seek help from a healthcare provider for proper diagnosis and treatment.

Can I Prevent SAD?

While SAD cannot be fully prevented, individuals with a history of the disorder can take proactive measures before seasonal changes occur. Starting therapy or treatment before the onset of symptoms, based on seasonal patterns, can be beneficial. Consulting with a healthcare provider can help you develop a personalized plan for managing SAD.

Where Can I Find More Information?

Substance Abuse and Mental Health Services Administration:
National Institute of Mental Health:
Crisis Prevention:
Suicide & Crisis Lifeline: Call or text 988 to be connected with a trained crisis counselor


1. American Psychiatric Association. Seasonal affective disorder (SAD). Accessed March 25, 2024.
2. Roecklein KA, Rohan KJ. Seasonal affective disorder. Psychiatry Edgmont. 2005;2(1):20-26.
3. American Foundation for Suicide Prevention. Suicide statistics. Accessed March 25, 2024.
4. CDC. Facts about suicide. May 8, 2023. Accessed March 25, 2024.
5. Cheung A, Dewa C, Michalak EE, et al. Direct health care costs of treating seasonal affective disorder: a comparison of light therapy and fluoxetine. Depress Res Treat. 2012;2012:628434.
6. Sohn CH, Lam RW. Update on the biology of seasonal affective disorder. CNS Spectr. 2005;10(8):635-646.
7. Wehr TA, Duncan WC Jr, Sher L, et al. A circadian signal of change of season in patients with seasonal affective disorder. Arch Gen Psychiatry. 2001;58(12):1108-1114.
8. Miller AL. Epidemiology, etiology, and natural treatment of seasonal affective disorder. Altern Med Rev. 2005;10(1):5-13.
9. Melrose S. Seasonal affective disorder: an overview of assessment and treatment approaches. Depress Res Treat. 2015;2015:178564.
10. Lavoie MP, Lam RW, Bouchard G, et al. Evidence of a biological effect of light therapy on the retina of patients with seasonal affective disorder. Biol Psychiatry. 2009;66(3):253-258.
11. Willeit M, Sitte HH, Thierry N, et al. Enhanced serotonin transporter function during depression in seasonal affective disorder. Neuropsychopharmacology. 2008;33(7):1503-1513.
12. Galima SV, Vogel SR, Kowalski AW. Seasonal affective disorder: common questions and answers. Am Fam Physician. 2020;102(11):668-672.
13. Kurlansik SL, Ibay AD. Seasonal affective disorder. Am Fam Physician. 2012;86(11):1037-1041.
14. Danilenko KV, Ivanova IA. Dawn simulation vs. bright light in seasonal affective disorder: treatment effects and subjective preference. J Affect Disord. 2015;180:87-89.
15. Jepson TL, Ernst ME, Kelly MW. Current perspectives on the management of seasonal affective disorder. J Am Pharm Assoc. 1999;39(6):822-829.
16. Thaler K, Delivuk M, Chapman A, et al. Second-generation antidepressants for seasonal affective disorder. Cochrane Database Syst Rev. 2011;(12):CD008591.
17. Martinez B, Kasper S, Ruhrmann S, Möller HJ. Hypericum in the treatment of seasonal affective disorders. J Geriatr Psychiatry Neurol. 1994;7(Suppl 1):S29-S33.
18. Wheatley D. Hypericum in seasonal affective disorder (SAD). Curr Med Res Opin. 1999;15(1):33-37.
19. Srinivasan V, De Berardis D, Shillcutt SD, Brzezinski A. Role of melatonin in mood disorders and the antidepressant effects of agomelatine. Expert Opin Investig Drugs. 2012;21(10):1503-1522.
20. Stewart AE, Roecklein KA, Tanner S, Kimlin MG. Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder. Med Hypotheses. 2014;83(5):517-525.
21. Kerr DCR, Zava DT, Piper WT, et al. Associations between vitamin D levels and depressive symptoms in healthy young adult women. Psychiatry Res. 2015;227(1):46-51.
22. Pinchasov BB, Shurgaja AM, Grischin OV, Putilov AA. Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light. Psychiatry Res. 2000;94(1):29-42.
23. Chang AM, Aeschbach D, Duffy JF, Czeisler CA. Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. Proc Natl Acad Sci U S A. 2015;112(4):1232-1237.
24. Leppämäki S, Partonen T, Vakkuri O, et al. Effect of controlled-release melatonin on sleep quality, mood, and quality of life in subjects with seasonal or weather-associated changes in mood and behaviour. Eur Neuropsychopharmacology. 2003;13(3):137-145.
25. Wirz-Justice A, Graw P, Kräuchi K, et al. “Natural” light treatment of seasonal affective disorder. J Affect Disord. 1996;37(2-3):109-120.
26. Partonen T, Leppämäki S, Hurme J, Lönnqvist J. Randomized trial of physical exercise alone or combined with bright light on mood and health-related quality of life. Psychol Med. 1998;28(6):1359-1364.
27. Michael DR. Seasonal affective disorder (SAD) treatment & management: approach considerations, bright-light therapy, psychotherapy. MedScape. December 9, 2020. Accessed March 26, 2024.

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