Shared joy is a double joy; shared sorrow is half a sorrow. - Swedish Proverb

What is Seasonal Affective Disorder?

Answers from the doctor who first described the condition

Norman E. Rosenthal, M.D.

What is Seasonal Affective Disorder (SAD)?

Seasonal Affective Disorder is a type of depression that occurs regularly, every autumn and winter, when the days get short and dark, though it may occur at other times as well. The reason it occurs mostly during the winter months is that one of the main causes of the condition is a lack of sunlight. Other situations in which people don’t get enough sunlight include cloudy or rainy periods at other times of year, living in dark places, and working for long hours in dark offices. Whenever there is insufficient sunlight, those people who are vulnerable to Seasonal Affective Disorder may develop symptoms.

There is also an opposite type of Seasonal Affective Disorder, called summer SAD, which I will discuss in more detail elsewhere on this page.

My colleagues and I first described SAD in a journal article in 1984, based on a group of people we studied in Maryland in the U.S. Since then, others have described the same condition in many different parts of the world, including both northern and southern hemispheres.

As you can imagine, the prevalence of SAD increases the further people live from the equator. In one study of people at four different locations in the U.S., for example, my colleagues and I found that in Florida, the prevalence of SAD was only 1.5% of the population, whereas in New Hampshire, it was almost 10%2.

Some people suffer during the fall and winter months to a lesser degree than those with full-blown SAD and are said to have Winter Blues (technically called subsyndromal-SAD).

It is common for people to experience the full syndrome of Seasonal Affective Disorder during certain winters, but the milder Winter Blues at other times. The severity of symptoms may vary with the severity of the winter, with changes in latitude (less severe if people move closer to the equator or go on vacation to a sunny place) or once people start treating their symptoms.

If you think a friend or loved one might be depressed, here is an article, “Seven Tell-Tale Signs of Depression in a Friend or Loved One“.

What Causes SAD and Who is Most Likely to Develop the Condition?

Besides the lack of environmental light, which is a major cause of SAD, there are two other leading causes: biological predisposition, and stress. People who are predisposed to developing SAD include those with family members with the condition, as well as other forms of depression. In addition, gender is a factor. Women are about four times as likely to develop SAD as men. During the winter months, people with SAD are less able to handle stress than they are at other times of year. For example, having to get to work early in the morning, to work long hours, or to meet deadlines are all particularly stressful for those with a tendency to develop SAD, especially when these stresses occur during the winter.

Several theories have been suggested to explain why some people develop SAD.

These include:

  1. Sluggish transmission in brain serotonin systems;
  2. Insensitivity of the eyes to environmental light; and
  3. Abnormal circadian (daily) rhythms

Some people with SAD may have abnormalities in the genes responsible for serotonin transmission or for the sensitivity of the retina to light (perhaps because of abnormalities in the retinal pigment called melanopsin. More than one of these explanations may exist at the same time. Light therapy, one of the leading treatments for SAD may work by reversing one or more of these.

Seasonal-Affective-DisorderHow Do You Treat Seasonal Affective Disorder?

The good news about SAD is that there are lots of things that you can do to treat it effectively. In my experience, when these treatments are added together (because a combination is usually better than any single treatment), most people can treat their SAD symptoms well enough to function through the winter – though you might never feel quite as good as you do in summer.

Here then, are the major ways for treating SAD, in more or less their order of effectiveness:

1. Light Therapy

Put simply, light therapy involves bringing more light into one’s environment during the dark days (winter, cloudy weather, basement apartments, windowless offices, etc). This can be done naturally by getting outdoors on a dark day, especially in the morning. Practically speaking, it is hard to do especially on a cold and busy winter day. You can bring more indoor light into your home or office by means of regular lamps. The most practical way, however, to treat yourself with artificial light therapy is by means of special light fixtures, also known as lightboxes.

When it comes to choosing a light box, there are many offerings on the marketplace. These are the important considerations in choosing a lightbox: (1) It should be of a certain size – the surface area from which the light comes should be at least one-foot square. In my opinion, the smaller boxes are less effective – though this has not been tested by research. (2) Fluorescents are best. The new LED-based light boxes have not been as well tested for safety and efficacy. (3) White is better than blue. Although the blue may seem cool, it just hasn’t been as well tested as the white, and some experts have voiced safety concerns about it.

There are many, many questions about how to use light therapy best. In my book Winter Blues: Everything You Need to Know to Beat SAD (Guilford, 2006), I provide answers to the 44 questions most commonly asked. You can also find more answers by reading my blog on this website. For example sometimes more light can be that much more helpful (On the Frontiers of SAD: How Much Light is Enough?).

2. Stress Management

During the winter, people with Seasonal Affective Disorder have a reduced ability to handle stress, which can push them deeper into depression. I recommend that you do whatever you can to minimize stress. This means thinking about winter ahead of time. For example, do not undertake projects with a spring deadline attached to them because you know ahead of time that that will put you under stress during the winter.

One of the most effective ways to reduce stress is meditation. I have been enormously helped in managing my own SAD symptoms since regularly practicing Transcendental Meditation (TM), and many others have found this practice equally helpful. Others have found relief from stress through other forms of meditation – such as mindfulness, which includes insight meditation (Vipassana), loving-kindness, open-field meditation (such as monitoring one’s breathing), and walking meditation. Yoga can also be highly beneficial for reducing stress and keeping you limber in the months when one tends to become a couch potato.

3. Exercise

Talking of being a couch potato, regular exercise can be an extremely helpful SAD-busting technique. You ought to do it for your general health anyway, so why not capitalize on the two-for-one benefit and do it for your mental health as well? I regularly walk briskly outdoors in the morning, which I greatly enjoy not only for the exercise, but also because it connects me with nature, my neighborhood, and my neighbors. There are many forms of exercise, however, and the greatest predictor of a successful exercise program is your ability to stick to it. One of my friends – a middle-aged woman – has decided to take up belly dancing as her chosen form of exercise, and loves it. Now, to be clear, I’m not advising that you all run out and take a belly dancing class, rather, that you do what you enjoy and find fun. That way you will stick with it and derive the maximum benefit.

4. Talk Therapy (Also known as psychotherapy)

Being depressed is lonely, and for many people, it helps to have a coach to guide you through the process. A good therapist will help you implement some of the suggestions listed in this section. In addition, there is evidence that cognitive behavior therapy (CBT) can be specifically helpful to people with SAD, not only helping them get through the winter but even reducing the chance that they will become depressed the following winter. Winter Blues contains an entire chapter that explains this highly effective and well-researched form of therapy and provides examples of how to implement these suggestions in your own life. Dr. Kelly Rohan, Associate Professor of Psychology at the University of Vermont, is a leading researcher in this field.

5. Antidepressant Medications

For many people, antidepressants are a valuable part of their SAD management regimen. These should be prescribed by someone with an understanding of SAD, who can incorporate them into the overall regimen. In general, the more effective the other aspects of an anti-SAD regimen are, the fewer antidepressants will be needed, which is a good thing as it minimizes side effects. On the other hand, if you do need antidepressants, as confirmed by a psychiatrist, I recommend that you use them. Remember, you may need different dosages of antidepressants at different points in the fall and winter as the amount of sunlight waxes and wanes. Many different forms of antidepressants can be helpful. In one study, my colleagues and I found that giving the antidepressant buproprion-XL in the autumn, before symptoms arose, helped prevent the subsequent onset of SAD symptoms.

6. Take Trips to Sunny Places

You know where those sunny places are but, unless you plan in advance, you may feel too tired, unmotivated, and down, to plan a trip when you need it the most. Take a look at a trip I took recently to Paradise Island in the Bahamas as “rescue medication” when my usual anti-SAD regimen wasn’t working.

Traveling to the Sun: The Ultimate Rescue Cure for the Winter Blues

7. Watch your diet

People with Seasonal Affective Disorder often crave sweets and starches. Although these may boost energy briefly, there is often a rebound when people feel tired and lethargic and are driven to – you guessed it – gorge on more sweets and starches. The unwelcome result is extra pounds on the hips or belly, which are hard to take off when winter is over, not to mention bad for your health.

Encourage people to eat diets high in proteins, vegetables, unprocessed foods, and complex carbohydrates. Check out my blog on the benefits of slow-cooked Irish steel-cut oatmeal, which can be made in a batch so as to provide breakfast for the entire week – a boon for the hassled SAD sufferer, struggling to get out the door on a winter morning.

8. Relocation

If all else fails, you can always move further south, though this is of course a major life change and needs to be carefully thought through. In Winter Blues, I outline some of the considerations required before such a major move is undertaken.


Need more information about SAD and the winter blues? Please see my book, Defeating SAD (Seasonal Affective Disorder): A Guide to Health and Happiness Through All Seasons.

For a visual on Seasonal Affective Disorder here is my infographic, below

Courtesy of: Norman Rosenthal