What is Seasonal Depression?

Seasonal depression, often called seasonal affective disorder (SAD), is a depression that occurs each year at the same time, usually starting in fall, worsening in winter, and ending in spring. It is more than just "the winter blues" or "cabin fever." A rare form of SAD, known as "summer depression," begins in late spring or early summer and ends in fall.

What are the symptoms of seasonal affective disorder?

People who suffer from SAD have many of the common signs of depression, including:

• Sadness

• Anxiety

• Irritability

• Loss of interest in usual activities

• Withdrawal from social activities

• Inability to concentrate

• Extreme fatigue and lack of energy

• A "leaden" sensation in the limbs

• Increased need for sleep

• Craving for carbohydrates, and weight gain

Symptoms of Summer SAD include:

• Weight loss

• Agitation and restlessness

• Trouble sleeping

• Decreased appetite

How common is seasonal affective disorder?

Approximately half a million people in the United States suffer from winter SAD, while 10 to 20 percent may suffer from a more mild form of winter blues. Three-quarters of the sufferers are women, and the depression usually starts in early adulthood. SAD also can occur in children and adolescents. Older adults are less likely to experience SAD.

This illness is more commonly seen in people who live in cloudy regions or at high latitudes (locations farther north or south of the equator). Individuals who relocate to higher latitudes are more likely to be affected by SAD.

What causes seasonal affective disorder?

The exact cause of this condition is not known, but evidence strongly suggests that, for those who are vulnerable to it, SAD is set off by changes in the availability of sunlight. One theory is that with less exposure to sunlight, the internal biological clock that regulates mood, sleep, and hormones is shifted. Exposure to light may reset the biological clock.

Another theory is that brain chemicals (neurotransmitters, such as serotonin) that transmit information between nerves may be changed in people with SAD. It is believed that exposure to light can correct these imbalances.

Melatonin, a chemical known to affect sleep patterns, may also play a role in seasonal affective disorder. Some have suggested that the lack of sunlight stimulates the production of melatonin in some individuals. This may be a factor in the symptoms of sluggishness and sleepiness.

How can I tell if I have seasonal affective disorder?

It is very important that you do not diagnose yourself. If you have symptoms of depression, see your doctor for a thorough assessment. Sometimes physical problems can cause depression. But other times, symptoms of SAD are part of a more complex psychiatric problem. A mental health professional typically can evaluate your pattern of symptoms and identify whether you have SAD or another type of mood disorder.

How is seasonal affective disorder treated?

Research now shows that phototherapy, also known as bright light therapy, is an effective treatment for SAD. Sometimes antidepressant medicine is used alone or in combination with light therapy. Spending time outdoors during the day can be helpful, as well as increasing the amount of sunlight you're exposed to at home and in the office.

Cognitive-behavioral therapy (CBT) is a very effective psychotherapeutic approach to seasonal affective disorder. A recent study demonstrated that CBT produced the longest-lasting effects of any treatment approach.

What is light therapy? Is it safe?

Light therapy, sometimes called phototherapy, is provided by a device that contains white fluorescent light tubes covered with a plastic screen to block ultraviolet rays. The intensity of light emitted (Lux) should be 10,000 Lux. The patient does not need to look directly into the light, but reads or eats while sitting in front of the device at a distance of two to three feet.

Light therapy is generally safe and well-tolerated. However, there are some situations in which it cannot be used (for example, conditions such as diabetes or retinopathies, certain medications) because of the potential risk of damage to the retina of the eye. Bright light therapy can cause hypomanic or manic symptoms; therefore, individuals with bipolar affective disorder need to have medical supervision in order to use light therapy.

Side effects of light therapy include:

• Eye strain

• Headache

• Irritability

• Fatigue

• Insomnia

At what time of the day should I use light therapy? For how long?

The timing of light therapy appears to affect the response. Recent studies suggest that morning light therapy is more effective than evening treatments. Using this treatment too late in the day may cause insomnia.

Many health professionals prefer to treat SAD with 10,000 Lux for 15 to 30 minutes every morning. Patients often see improvement within two to four days, and reach full benefits within two weeks. The symptoms of SAD return quickly after light therapy is stopped, so light treatment should be continued throughout the entire season of low sunlight.

Even though they generate enough light, tanning beds should not be used to treat SAD. The amount of ultraviolet (UV) rays they produce is harmful to the skin and eyes.

Can I prevent seasonal affective disorder?

If you think you have symptoms of SAD, see your doctor for a thorough examination. Your doctor will want to make sure that these symptoms are not caused by another psychiatric condition or major medical illness.

If you have been diagnosed with SAD, here are some things you can do to help keep it from coming back:

• Begin using a light box at the start of the fall season, even before you feel winter SAD coming on.

• Try to spend some amount of time outside every day, even when it's very cloudy. The effects of daylight are still helpful.

• Eat a well-balanced diet and include sufficient amounts of vitamins and minerals as recommended by the FDA. This will help you have more energy even though your body is craving starchy and sweet foods.

• Try exercising for 30 minutes a day, three times a week.

• Stay involved with your social circle and regular activities. This can be a tremendous means of support during winter months.

• Consider consulting a mental health professional trained in cognitive behavior therapy, which has been demonstrated as an effective treatment for SAD.

• Talk to your doctor about antidepressant medication if your symptoms are severe or continue even after treatments such as bright light therapy.

If your symptoms become severe and you or someone you know, are having thoughts of suicide, call your doctor right away or go to the nearest emergency room.

© Copyright 1995-2023 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional health information, please contact the Center for Consumer Health Information at the Cleveland Clinic (216) 444-3771 ☎ or toll-free (800) 223-2273 ☎ extension 43771. If you prefer, you may visit Cleveland Clinic

Healthy Community Initiative (HCI):
#HealthyCommunitiesInitiative

The Healthy Community Initiative is a collaborative effort between Cleveland Clinic and community partners to promote optimal health and wellness. Based on the community health needs assessment and utilizing combined resources within our local communities, Healthy Community Initiative programs will be customized around three core areas: education, nutrition and physical activity.

Live Long Lyndhurst Health and Wellness Initiative (HWI):
#LiveLongLyndhurst

Live Long Lyndhurst is a Health and Wellness Initiative between the City of Lyndhurst, Cleveland Clinic Community Outreach, Legacy Village, Cleveland Metroparks at Acacia, The Fedeli Group, the YMCA, South Euclid - Lyndhurst Schools, Second Sole and Anthem BlueCross BlueShield.