Seasonal affective disorder (SAD) is a type of depression that comes and goes with the four seasons, typically manifesting during the cold autumn and winter months, when the days are shorter, darker, and chillier.

According to the National Institute of Mental Health, the main risk factors for SAD are age, sex, distance from the equator (since regions farther to the north and south tend to have shorter days and less sunlight in winter), and a history of depression or other mood disorders.

Studies have shown that "young adults and women are most likely to experience SAD with the reported gender difference ranging from 2:1 to 9:1."

People with SAD can experience a range of symptoms, but some of the most commonly reported ones include a sense of fatigue paired with oversleeping, chronically low moods, and strong cravings for carbohydrates, which can lead to excessive weight gain.

SAD can seriously impact productivity and day-to-day lifestyle, as the symptoms — if severe — can prevent individuals from going out, seeing other people, and engaging in some of the normal activities that they would otherwise pursue.

So what can you do if the winter months are getting you down? How can you cope with the lack of motivation, feelings of hopelessness, and debilitating fatigue? Here, we give you some tips on how to tackle SAD head-on.

Hunt down that light

Lack of exposure to natural light is one of the apparent reasons behind winter SAD, so it doesn't come as a surprise that light therapy — also known as "phototherapy" — would be beneficial in keeping the symptoms at bay.

A light box can help to reduce the symptoms of SAD.

Many studies have indicated that light therapy is usually helpful in treating this seasonal disorder, and for this purpose, you can use one of the many dedicated light boxes that are now available on the market.

But to be effective, you should make sure that the light box generates at least 10,000 lux — 100 times stronger than a normal lightbulb, meaning that a regular desk lamp won't do — and that it has white or blue (not yellow) light.

Also, check that the light box was especially made to treat SAD, depression, and other mood disorders, and that it's not made for a different purpose (such as treating psoriasis or other skin conditions).

Light boxes for skin treatments are another kettle of fish altogether, as they emit ultraviolet (UV) B, which is not safe for the retina. Instead, dedicated SAD treatment light boxes filter out UVs, so they're safe to use.

Dr. Norman Ronsenthal — who first described SAD's symptoms and pushed for it to be recognized as a valid disorder — offers some advice on how to use light therapy in his book, Winter Blues: Everything You Need to Know to Beat Seasonal Affective Disorder. He writes:

Obtain a suitable light box.

Set the light box up in a convenient place at home or at work, or both.

Sit in front of the light box [...] between 20 and 90 minutes each day.

Try to get as much of your light therapy as early in the morning as possible.

Be sure to sit in such a way that the correct amount of light falls on your eyes. [Dr. Marlynn Wei says it should be placed at eye level or higher, 2 feet away from you.]

Repeat this procedure each day throughout the season of risk.

At the same time, you can add to the beneficial effects of light therapy by making a little extra effort to "hunt down" natural daylight, if possible, and take advantage of it as much as you can.

You could do this by waking up earlier in the morning and going outside where the sunshine is, for as long as it lasts, to allow yourself to feel as though you're soaking in the light and taking advantage of the whole day.

Eat well, and watch out for the carbs

Research has shown that individuals with SAD tend to eat more carbohydrate-rich foods, especially sweets and starchy foods. They also have a tendency to overeat during these periods of "seasonal lows," so it's important that they look after their diets in order to feel more energized.

Over the winter months, as we get less and less sunlight, vitamin D is insufficiently produced in our bodies. Research has also suggested that ensuring we get enough vitamin D may help to prevent and manage depression.

To make sure that you're getting enough vitamin D during autumn and winter, you could take dietary supplements. Vitamin D is also found in a range of foods that you can easily incorporate into your daily meals.

Salmon, for instance, is naturally rich in D-3, though some studies suggest that wild-caught salmon contains much larger amounts of the vitamin than farmed salmon.

Eggs are a good source of the vitamins D-2 and D-3, and mushrooms also have a high D-2 content, though research suggests that we should stick to wild mushrooms rather than cultivated ones.

Some studies also suggest that people with mood disorders may have an omega-3 fatty acid deficit, and so supplementation of this nutrient may help to keep symptoms in check.

According to the National Institutes of Health (NIH), some good food sources of omega-3 include various types of fish (salmon, herring trout, and mackerel), chia seeds, flaxseed, and soybean.

Also, research published last year in the American Journal of Public Health points to fruit and vegetables as the foods of choice when it comes to increasing happiness and well-being.

"Eating fruit and vegetables apparently boosts our happiness far more quickly than it improves human [physical] health," notes study co-author Prof. Andrew Oswald.

The psychological benefits of fruit and vegetable consumption were confirmed by a recent study, from February this year, which focused on the positive effect of a "green" diet on young adults — one of the groups most at risk of SAD.

Make an effort to stay active

Precisely because some of the main symptoms of SAD are fatigue and lethargy, specialists advise that making an effort to stay physically active can offer a boost of energy and improve mood.

A review of existing studies surrounding SAD and the effects of exercise on this disorder suggests that the low moods and other symptoms involved in it may be caused by disruptions to the body's circadian rhythm. The circadian rhythm regulates our sleep, eating, and activity patterns according to day-night cycles.

Review author Benny Peiser — from the Research Institute for Sport and Exercise Sciences at Liverpool John Moore University in the United Kingdom — explains that taking part in regular physical exercise during the autumn and winter months can help to maintain an appropriate circadian rhythm, thereby keeping SAD symptoms at bay.

A study recently covered by Medical News Today also demonstrates that even low-intensity exercise done for as little as 1 hour per week can effectively counteract depression.

Don't give in to reclusiveness

On those dark, cold days, you may be sorely tempted to just stay inside and hide from the weather and world alike. If you have more severe SAD symptoms, going out may seem unachievable, but if you want to keep the low moods and lethargy at bay, then you should do your best to resist these solitary tendencies.

Much the same as light exercise, studies show that a leisurely walk in the great outdoors can improve your mood and well-being.

Just taking one moment every day to notice a detail in your natural surroundings, and asking yourself what feelings it elicits, can make you feel happier and more sociable, according to research from the University of British Columbia in Canada.

The American Psychological Association advise that you keep in touch with friends and family, go out with them, and speak to trusted people about what you're experiencing. Enlisting someone else's help in keeping you active, and helping you get out of your shell during the cold months, may make it easier to cope with the effects of SAD.

Advice regarding how best to cope with SAD from Johns Hopkins Medicine also includes finding a winter-appropriate hobby that will both keep you busy and give you pleasure, such as a DIY project or a winter sport.

Moreover, don't forget that there is help available for people who experience SAD. Cognitive behavioral therapy has been proven to be effective in the treatment of this disorder, and a specialist will be able to recommend antidepressants if you find yourself struggling.

If you experience SAD, let us know what your strategy is for managing the symptoms and making the most of the holiday season.