As the Earth’s north pole tilts away from the sun, inhabits of the northern hemisphere prepare for some of the darkest and coldest days of the year. While some people start hanging blinking lights, throwing up decorated pine trees in their house, and preparing gifts for loved ones, others suffer from Christmas depression, and some battle an even more severe condition known appropriately as SAD.

What is SAD?

The term seasonal affective disorder was coined in the 1990s by the American Psychiatric Association (APA). SAD is closely related to other depressive disorders, but it varies in that the dark, gloomy symptoms of SAD visit on a seasonal schedule, usually in the fall or winter, although a smaller number of people are also affected by summer blues.

People with SAD are heavily impacted by the darker part of the year. Days are shorter, nights are longer, and all life seems to die. Grass turns brown, trees lose their leaves, animals migrate and hibernate, butterflies and bumblebees disappear, and the cold keeps people holed up indoors. This is a significant change from warmer months which can be spent interacting with nature and other people while soaking up mood-boosting rays of sunlight. The darkness of winter can put people into a sluggish and sleep-like state, causing them to feel as if they will never be warm or see the sun again.

People who experience seasonal depression in the winter feel listless and dreary with a tendency to oversleep and overeat. People with summer SAD feel the opposite. They often experience excess energy which can lead to restless thoughts, wired wakefulness at night, and a sharp drop in appetite.  


SAD tends to affect certain groups more often: women, those who are younger, those who live far from the equator where there is less sunlight, and those whose families have a history of depression, bipolar disorder, or SAD. It is uncertain what exactly causes seasonal depression, but some studies speculate that it has to do with each individual’s biological clock and levels of serotonin and melatonin. Dr. Norman E. Rosenthal, a psychiatrist at Georgetown University Medical Center, believes that SAD stems from a person’s insensitivity to light. He explains in his book, Winter Blues: Everything You Need to Know to Beat Seasonal Affective Disorder(Guilford Press, 2005), that most of us go through winter on a relatively even keel because exposure to indoor lighting helps offset the lack of natural light. But indoor light may be too weak for people with SAD. Rosenthal theorizes that a lack of, or insensitivity to, light may disrupt brain processes influenced by the mood-setting chemicals serotonin and dopamine.

If left untreated, SAD can lead to social withdrawal, reduced ability to work or attend school, substance abuse, other mental health disorders, and suicidal thoughts or behavior.

Lighten Up

If you do not have seasonal affective disorder but are at risk for developing it, it is wise to take measures to help keep your spirits up during certain seasons. Make the time for exercise. In the winter, people are often less active; they don’t go for walks outside, they don’t visit the park or play sports. To keep your activity levels up, you can practice an indoor exercise routine by following a fitness video, running on a treadmill, lifting weights, jumping rope, or doing yoga. Exercise can give your mood a healthy boost and lower your stress levels.

You can look for special lights that are designed to mimic sunlight called light therapy boxes. Light therapy is thought to be effective in treating SAD, other depressive disorders, and sleep disorders. It’s a relatively safe treatment with little possible side-effects.

If you experience SAD in the summer, it would probably be best to keep away from light. It is thought that summer SAD is due to too much sun. Too much sunlight also turns off production of melatonin, making it more difficult for restless sleepers to get the refreshing rest they need.

Treating SAD

If you have been diagnosed with SAD, research published in Biological Psychiatry indicates that taking antidepressant medication in autumn, before the mood declines, may help to alleviate symptoms. If your doctor recommends it, increasing the dosage of your existing medication or switching to another pharmaceutical may help.

Light therapy can help restore balance to unbalanced circadian rhythms. Most studies recommend that SAD sufferers receive about 30 to 45 minutes of exposure to a 10,000-lux light source daily for light therapy to be effective. Keep in mind that some light therapy boxes become less bright over time and may need to be replaced each year if used regularly. If eye damage is a concern for you, some light boxes are designed to not emit light in the blue part of the spectrum, which is believed to be more damaging to the retina.

Spending more time outdoors while the sun is up can be an effective treatment for SAD. In the 1990s, Swiss researchers designed a trial that compared a one-hour walk each morning to sitting in front of a light box for half an hour. Those who went for a walk in the sun received a much greater mood lift than those who basked in artificial light. Finally, consider attending therapy sessions or joining a support group. Sometimes talking things out is the best way to endure, understand and overcome this difficult problem.


  • Kevin Gardner loves writing about technology and the impact it has on our day to day lives. When not writing, Kevin enjoys working out at the gym and hiking in the mountains. Follow his adventures on twitter.