Recent research suggests that most people in the northern United States do experience seasonal changes in mood, behavior or even ability. For most of us the changes aren’t serious, but for some people winter can be disabling.

A full blown case of SAD can bring deep depression and difficulty in functioning on the job. But even mild seasonal changes can make it harder for you to do your best at work. Among the symptoms of SAD are these:

Decreased concentration, productivity, interest and creativity. An inability to complete tasks. Trouble getting along with others. Low energy. Increased susceptibility to colds, flu, sore muscles and other physical problems.

According to experts at Georgetown University, in the Washington, D.C. area about five percent of people suffer from SAD, typically during December through February. More than twice that many suffer from SAD’s less serious cousin, dubbed the “winter blues.” And most of the rest of us are vulnerable to some seasonal symptoms.

The biggest environmental trigger of SAD is light deprivation, perhaps because our serotonin levels vary according to the amount of light we receive. The further away you are from the equator, the more likely you are to be troubled by SAD. But you can experience some symptoms no matter where you are, perhaps because the weather is very cloudy, or because you work in a dark office and never get outside to see the sun.

We can’t change the weather, but there are ways to alleviate winter’s effects, including these:

• Let in the Light. Many people can mitigate the impact of SAD by allowing themselves to be exposed to more light. That can mean opening your drapes, spending some time outside every day, or ensuring that your workplace has proper lighting. An effective and well-studied approach is to sit in front of a special light fixture (with a filter to remove most ultraviolet rays from regular fluorescent bulbs) for at least 20 minutes a day.
  
  
• Exercise. There’s growing evidence that regular exercise can mitigate depression, so it’s not surprising that exercise can help with SAD, as well. Doctors recommend that you do something that you enjoy. And you will enhance the anti-depressant effect if you do it outdoors and increase your exposure to light at the same time.
  
  
• Eat right. If you’re suffering from winter blues, you may crave sweets and other comfort foods, but indulging in dishes rich in carbohydrates will actually leave you feeling worse in the long run. SAD is associated with exaggerated insulin responses to simple carbs, which means that your energy will drop and you’ll be hungry again soon after eating. And all those carbs cause weight gain, which can make you feel even worse.
  
  
• Have some fun. Engaging in pleasant activities can elevate your mood and increase your energy level. If you know that you tend to be down in the winter, schedule some enjoyable events. Indulge in massage or other therapies that will help you to relax and reduce your stress level.
  
  
• Reach out. When winter hits, you may feel like hibernating. But staying home alone might make you feel even worse. Arrange some social activities, call your friends or do whatever else will help you to feel connected to other people.
  
  
• Control your negative thoughts. Like many victims of depression, SAD sufferers may find themselves experiencing negative thought patterns. Some therapists say that you can successfully challenge the core beliefs that seem to drive the repetitive patterns. One approach suggests that you can break the patterns by writing down your negative thoughts, then systematically disputing them.
  
  
• See a doctor or therapist. For many of us, self help will be all it takes to combat the special challenges of winter darkness. For others, however, relief might require medication or other treatment.