Seasonal Affective Disorder (SAD)

Reviewed on 11/8/2021

What Is Seasonal Affective Disorder (SAD, Seasonal Depression)?

Winter season
Risk factors for SAD include living in geographical locations that are dark or cloudy during the winter.

Seasonal affective disorder (SAD) is a type of depression that is tied to seasons of the year. Historical facts about SAD include that as early as 400 BC, Hippocrates described changes in seasons as causing illness. Two hundred years later, light therapy was being recommended as a treatment for people described as "lethargic" or suffering from "gloom." Most people with SAD are depressed only during the late fall and winter (sometimes called the "winter blues") and not during the spring or summer. That many cultures celebrate a number of holidays during the winter can be an additional stress for people with SAD. A small number of SAD sufferers, however, are depressed only during the late spring and summer. In contrast to SAD, other forms of recurrent depression, like bipolar or unipolar depression, occur independently of the time of year.

SAD is most common in young adult women, although it can affect men or women of any age. SAD affects people in both hemispheres and is rarely within 30 degrees latitude of the equator. Some people may have a milder form of seasonal mood change.

Like all types of clinical depression, SAD can have a devastating effect on a person's life. Fortunately, almost all people with SAD can be helped with available therapies.

What Causes Seasonal Affective Disorder?

The exact causes of seasonal affective disorder (SAD) are unknown.

  • Chemical changes in the brain caused by changes in the amount of sunlight are probably involved. Risk factors for SAD include living in geographical locations that are dark or cloudy during the winter.
  • A tendency to have SAD may run in some families.
  • Given how often alcohol abuse and dependence occur in individuals with SAD, there is thought to be a possible genetic link between having either illness.
  • Low levels of vitamin D seem to be a risk factor for developing a number of mood disorders, including SAD.

What Are the Symptoms of Seasonal Affective Disorder?

Seasonal affective disorder (SAD) may have some of the same signs and symptoms as other types of depression. The stress of anticipating the onset of SAD often results in the sufferer having anxiety months before SAD symptoms begin each year.

  • Most people have only some of these symptoms, not all.
    • Depressed mood
    • Loss of interest in usually enjoyable activities
    • Fatigue or loss of energy
    • Feelings of worthlessness or hopelessness
    • Poor concentration, indecisiveness
    • Recurrent thoughts of death or suicide
  • The symptoms of SAD come back every year, and for any specific person, they tend to come and go at about the same time each year.
  • Winter SAD is typically characterized by
    • sleeping more than usual;
    • craving for sugar, starchy foods, or alcohol;
    • weight gain;
    • irritability;
    • conflicts with other people;
    • the heaviness of arms and legs;
    • behavior disturbances (in children).
  • People with winter SAD may seek out light places or sunlight, or like to have lots of artificial lights on.
  • Summer SAD is generally accompanied by some of the following signs and symptoms:

When Should I Call the Doctor About Seasonal Affective Disorder?

Seek medical care if you think you have a seasonal affective disorder or another type of depression, or if any of the following occur:

  • Feelings of extreme sadness, hopelessness, or emptiness
  • Inability to get out of bed or carry on normal activities
  • Persistent loss of energy or increased need for sleep
  • Unexplained change in appetite for food
  • Changes in behavior that cause problems with family, friends, or work
  • Feelings of wanting to die, wanting to commit suicide, or hurting yourself

How Do Medical Professionals Diagnose Seasonal Affective Disorder?

No single laboratory test or series of tests are available to detect the seasonal affective disorder. Your health care professional will make the diagnosis from your history of symptoms, current signs and symptoms, medical interview, and examination.

What Are the Home Remedies for Seasonal Affective Disorder?

The following activities or lifestyle changes may help prevent seasonal affective disorder or improve the symptoms:

  • Spend at least 30 minutes outside every day.
  • Set a timer on a light to go on early in the morning in the bedroom.
  • Use a dawn simulator for a more naturalistic artificial dawn.
  • Take daily walks outside.
  • Increase indoor lighting with regular lamps and fixtures.
  • Take a vitamin D supplement.

What Is the Treatment for Seasonal Affective Disorder?

Bright-light therapy is exposure to bright artificial light, which is more brilliant than usual home or office lighting. Bright-light therapy relieves symptoms for about two-thirds of people with seasonal affective disorder.

  • Bright-light therapy products are available for sale and have a wide range of costs. They range from 2,500-10,000 lux. Many experts recommend that 10,000 lux be used, for adults, teens, or during childhood. Bright-light therapy has also been found to be effective during pregnancy. Only devices that filter out harmful ultraviolet waves should be used. Types of devices include light panels or boxes, blankets, and visors.
  • The bright-light source should be placed at eye level. Although staring at the light source is not recommended, the light must enter the eyes if it works. (Simple skin exposure does not work.) An approved bright-light therapy device should not harm the eyes if used as recommended.
  • About 30 minutes of exposure to 10,000 lux each day is enough to relieve symptoms in most people. Others require greater exposure, as long as 45 minutes twice a day. You may need some trial and error to find the right amount. Your health care professional will guide you.
  • Properly used, bright-light therapy has few side effects. A few people have reported eyestrain, headache, fatigue, irritability, sensitivity to light, or inability to sleep (only if therapy is used late in the day).
  • Certain medications make you more sensitive to light. Be sure to inform your health care professional of all the medications you are taking, including nonprescription medications and dietary supplements.
  • Tanning beds should not be used for bright-light therapy as they do not filter out harmful ultraviolet waves.
  • You may notice an improvement in symptoms within a few days, or it may take as long as three to four weeks after starting therapy.

Cognitive-behavioral therapy (CBT) has been proven to effectively treat seasonal depression or seasonal affective disorder (SAD).

What Are the Medications for Seasonal Affective Disorder?

Antidepressant medications are useful for people who need further treatment because their symptoms improve only slightly or not at all with bright-light therapy. Most of these people are treated with antidepressant medication. To read more about antidepressants, see Understanding Antidepressant Medications.

What Is Other Therapy for Seasonal Affective Disorder?

St. John's wort: It is unclear whether this herb will improve some of the symptoms of seasonal affective disorder (SAD), but it increases sensitivity to light, which may rule out bright-light therapy. Researchers are still looking at whether this treatment is appropriate for people with SAD. Other natural remedies like kava and acupuncture are being studied to explore whether or not they can effectively treat SAD.

What Is the Follow-up for Seasonal Affective Disorder?

  • Learn as much as you can about the seasonal affective disorder (SAD).
  • Do not feel guilty; understand that SAD is caused by a chemical abnormality that you have little control over.
  • Explore support groups to help you cope with the disorder.
  • Follow the treatment recommendations of your health care professional.

How Can I Prevent Seasonal Affective Disorder?

  • Spending at least 30 minutes outdoors every day may help prevent seasonal affective disorder (SAD).
  • Approaching the season of depression with a positive attitude and planning activities you enjoy may be another example of how to avoid SAD.
  • Try to spend time outdoors every day, especially during the months when SAD affects you most. Midday, when the light is strongest, is the best time to be outdoors.
  • Physical activities, such as walking, may also help relieve symptoms.
  • If taking antidepressant medication, take as directed and do not stop or change your dose without consulting your health care professional.

What Is the Prognosis for Seasonal Affective Disorder?

If left untreated, the seasonal affective disorder can become more severe and have a negative prognosis. Severe depression can cause damage to physical and mental health, relationships with others, job effectiveness, and enjoyment of life. Very severe depression can cause a person to contemplate or commit suicide or other self-harm.

Support Groups and Counseling for Seasonal Affective Disorder

Counseling also called psychotherapy, may be necessary to help you cope with fear or guilt about the seasonal affective disorder (SAD). It may help you relax, accept the disorder, and cope with the limits SAD puts on you. Complimentary activities such as meditation, relaxation, and aerobic exercise may have similar effects.

Depression and Bipolar Support Alliance

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Seasonal Affective Disorder Symptom


  • Anxiety is a feeling of nervousness, apprehension, fear, or worry. Some fears and worries are justified, such as worry about a loved one or in anticipation of taking a quiz, test, or other examination. Problem anxiety interferes with the sufferer's ability to sleep or otherwise function.
  • It is noteworthy that teenagers are particularly susceptible to having irritability as a symptom of a number of emotional problems, including anxiety.
  • Anxiety may occur without a cause, or it may occur based on a real situation but may be out of proportion to what would normally be expected. Severe anxiety can have a serious impact on daily life.
Reviewed on 11/8/2021
Medically reviewed by Aimee V. HachigianGould, MD; American Board of Orthopaedic Surgery


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