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Affecting approximately 3 million Americans annually – or about five percent of the U.S. population – seasonal affective disorder (SAD) is a cyclical depression related to the shorter daylight hours and reduced sunshine in the fall and winter seasons, but it can also occur in the spring and summer. Going beyond just a general malaise or the winter blues, it is an enduring sense of feeling down, discouraged, fatigued, moody or unmotivated. While many of us periodically experience some low days or lack of energy – and perhaps more frequently in the grey, cold, gloomy days of winter – SAD is more severe and persistent over months.

The good news is that SAD can be treated and overcome. The key is understanding its causes and risk factors, identifying the symptoms and actively pursuing and following treatment until one recovers. Here is important information on combating seasonal affective disorder:

Causes and Risk Factors

Although the specific cause of SAD is unknown, the Mayo Clinic points to the following influencers:

  1. Circadian rhythms – Decreased levels of daylight and sunshine can impact the body’s internal clock and lead to depression.
  2. Serotonin levels – Serotonin is a neurotransmitter that affects mood, and reduced sunlight can lower the level of this brain chemical and thereby trigger depression.
  3. Melatonin levels – Playing a role in the body’s mood and sleep levels, melatonin levels can shift with the change in seasons.
  4. Vitamin D deficiency – Vitamin D insufficiency plays a role in serotonin levels.

Risk factors include:

  1. Female: SAD is diagnosed more often in women than in men. Four out of five people diagnosed with SAD are women.
  2. Age: Younger people have a higher risk of winter SAD, and the main age of onset is typically between 20-30 years old.
  3. Family history: SAD is more likely to occur in those with relatives who suffer from SAD or depression.
  4. Clinical depression or bipolar disorder: Having these conditions may cause depression symptoms to worsen seasonally.
  5. Physical location: SAD is more prevalent among people who live far north or south of the equator, where there is significantly decreased sunlight during the winter months.


SAD is considered a subtype of major depression, and winter-onset symptoms typically include:

  • Irritability
  • Fatigue or low energy
  • Problems getting along with others
  • Hypersensitivity to rejection
  • Difficulty concentrating
  • Heavy feeling in the arms or legs
  • Oversleeping
  • Appetite changes, especially craving foods high in carbohydrates
  • Weight gain
  • Weakened immune system
  • Social withdrawal

Spring-summer SAD has slightly different symptoms, such as:

  • Depression
  • Insomnia
  • Weight loss
  • Poor appetite
  • Agitation or anxiety
  • Restlessness

SAD should always be treated, and individuals shouldn’t brush off these feelings or simply try to muddle through, particularly if more severe symptoms arise, such as persistent social withdrawal, social or work problems, substance abuse or suicidal thoughts or behavior.

Diagnosis and Treatment

It’s important to see a medical professional for an evaluation and potential diagnosis of SAD, which can in and of itself be difficult for those who are feeling depressed and unmotivated. But taking this first step is critical to recovery.

Diagnosing SAD often includes a physical exam, which checks for underlying health problems; lab tests such as a thyroid test or complete blood count; and a psychological evaluation. A mental health professional evaluates information about mood, thoughts, feelings and behavior patterns, weighing these symptoms against the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which lists specific criteria that define SAD. According to the DSM-5, a diagnosis of SAD can be made after two consecutive occurrences of depression that occur and end at approximately the same time every year, with the symptoms subsiding the remaining months.

Treatment regimens can vary, but tend to consist of one or several of the following:

  • Light therapy – Here, individuals sit for 30 minutes to two hours in front of a light box that simulates outdoor light and thereby stimulates specific brain chemicals related to mood. Or they use another type of light in the bedroom that goes on in the morning as one sleeps and gradually gets brighter, just like a sunrise. With few side effects, and with relatively rapid relief, light treatment is highly effective for most SAD sufferers. Doctors can provide guidance on what type of light box to purchase.
  • Medications – Antidepressants can help SAD sufferers better regulate their mood, and can be prescribed before symptoms appear. Patients may need to try different medications to identify the best treatment, and it may take a few weeks before antidepressants take effect in the body. And once prescribed medication, patients must regularly take the recommended dosage and adhere to the treatment plan.
  • Psychotherapy – A counselor or mental health professional can help those with SAD better manage stress, implement coping mechanisms and identify and replace negative thoughts and behaviors that worsen the condition.
  • Alternative therapies – Although more research is needed on these treatment options for SAD, they have been successful for some people These include taking supplements such as St. John’s wort, SAMe, melatonin and omega-3 fatty acids. However, supplements can interact with other prescriptions, so SAD sufferers should first speak with their doctor about a safe treatment plan.
  • Mind-body options – Activities such as yoga, meditation, guided imagery, acupuncture and massage therapy also can deliver physical and psychological relief when used in conjunction with other treatments. Some individuals keep a journal to help express and sort out emotions as well.
  • Environmental adjustments – Open the blinds and curtains at home, put the desk near a window if possible, consider adding a skylight and trim trees or bushes that block out the sun. Replace light bulbs with those that replicate natural light.
  • Get outside – Bundle up if necessary and take a walk, run errands on foot, or skip the gym and jog in the neighborhood instead. Fresh air and outdoor light are invigorating, boost energy and can enhance mood.
  • Exercise – Stimulate endorphins with regular workouts, which are an effective treatment for depression. Exercise increases energy, improves self-efficacy and leads to feelings of accomplishment. And going to a health club reduces social isolation and stimulates interaction.
  • Socialize – In addition to attending a health club, individuals with SAD should make regular, ongoing efforts to combat withdrawal, such as signing up for a class, volunteering at a local organization, joining a special interest club or becoming a member of a church. Reaching out to meet with friends helps limit loneliness.
  • Foster good health – Eating healthy and getting enough sleep go a long way in helping manage mood and maintain a positive perspective. Guard against excessive intake of alcohol, caffeine or drugs.
  • Take control daily – Getting organized, setting goals, developing and accomplishing to-do lists and following a daily regimen help provide purpose and direction, which can combat depression.
  • Take a vacation – If possible, treat winter-onset SAD with a visit a sunny, warm location; and address summer SAD with a trip to a cooler location.


Unfortunately, there is no proven way to prevent the onset of SAD; however, given its seasonal pattern, it can be predictable. Therefore, individuals may choose to begin treatment in the fall before symptoms emerge, and then continue well into spring or summer when symptoms generally have disappeared.