A gloomy day can put many people in a bad mood. But for a small percentage of the population, a whole season can spiral into a serious depression called Seasonal Affective Disorder (SAD).

SAD strikes 1 to 10 percent of the population every year, according to a 2009 journal review in Physician and Sportsmedicine.

The causes behind SAD are still unknown, but reports of successful treatments using light therapy have led to a theory that dwindling daylight hours during fall and winter months interrupts some people's circadian rhythms causing depression, according to the American Academy of Sleep Medicine and the National Institutes of Health (NIH)).


A person with SAD often starts to feel depression symptoms in the autumn and feel gradually worse during winter months, according to the NIH.

While some forms of depression contribute to weight loss, SAD suffers often have increased appetite and weight gain. SAD is also marked by daytime sleepiness and a lack of energy.

Unhappiness, irritability, a lack of interest in usual hobbies and withdrawing from friends and family are all symptoms of SAD, according to the NIH.

While many symptoms of SAD parallel symptoms of depression, SAD sufferers  go through a yearly cycle of depressive symptoms followed by a time when they are free from symptoms.

Diagnosis & Tests

Doctors diagnose SAD through a series of questions about symptoms. Usually physical tests are only required to rule out other causes of depressive symptoms. Some-times a psychologic evaluation is needed for severe forms of SAD, according to the NIH.

SAD is considered a subtype of depression or bipolar disorder and can be difficult to distinguish from other psychological problems, according to the Mayo Clinic.

To be diagnosed with SAD, usually a person must meet the criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM), specifically:  The person has experienced depression and other symptoms for at least two consecutive years during the same season every year. The periods of depression have been followed by periods without depression and there are no other explanations for the changes in mood or behavior.

Most people with SAD experience depressive symptoms in fall and winter. However, a rare form of SAD strikes people in the summer months.

Sufferers of summer onset SAD are more likely to have anxiety, irritability, weight loss, insomnia and increased sex drive, according to the Mayo Clinic.

Treatments & Medications

Doctors recommend people afflicted with SAD try to get as much natural daylight as possible by taking walks outside or sitting near windows.

Exercising and staying connected with family and friends can also ease SAD symptoms, according to the Mayo Clinic.

Many people with SAD turn to “light therapy.” While light therapy is very popular, studies have not shown how light therapy works, or exactly how effective it is, ac-cording to the Mayo Clinic.

Doctors recommend SAD sufferers get medical advice before trying light therapy on their own.

Light therapy involves sitting in front of a specialized florescent bulb to mimic day-light. Typically a person sits in front of the “light box” for 30 minutes a day, often be-fore the sun rises.

A person trying light therapy should see their symptoms improve within three to four weeks if light therapy will help, according to the NIH. Otherwise light therapy may not be the right treatment for them.

Doctors may prescribe antidepressants for people suffering from SAD. Common  drugs prescribed for SAD include bupropion (Wellbutrin XL), paroxetine (Paxil), sertraline (Zoloft) and fluoxetine (Prozac), according to the Mayo Clinic.

Psychotherapy may help people manage the depressive symptoms of SAD as well.

Some people have tried St. John's Wort and melatonin to combat the symptoms of SAD, however these might interfere with medications and have unwanted side effects, so it's best to speak with a doctor before trying these remedies.

According to the Mayo Clinic, some studies have shown Omega-3 fatty acids can reduce depressive symptoms. Omega-3s are most often found in cold water fish, flax-seed and walnuts.