Seasonal Affective Disorder: Diet and Lifestyle Interventions

By Anne Danahy, MS, RD, LDN

Seasonal affective disorder (SAD) is a type of mood disorder or depression, which occurs consistently in the fall and winter, and resolves in the spring and summer. Symptoms of SAD include:

  • Feeling sad, anxious, or “empty”
  • Irritability
  • Loss of interest in activities you usually enjoy
  • Fatigue
  • Decreased energy
  • Heavy, leaden feeling in arms or legs
  • Changes in weight, especially weight gain
  • Changes in appetite, usually an increased craving for carbohydrate foods

Risk Factors:

Seasonal Affective DisorderIt is estimated that SAD affects nearly one half million Americans each year, with women more likely to suffer from seasonal depression than men, and younger adults more at risk than older adults. Those who live furthest from the equator are more likely to experience SAD.

Research suggests that SAD is triggered by a reduction in the amount of sunlight or daylight, which upsets the body’s natural clock. A change in seasons can affect production of the hormone melatonin, which plays a part in regulating sleep and mood. Reduced exposure to sunlight can also negatively impact production of the serotonin, a neurotransmitter that affects mood.

Although diet and sedentary lifestyle are not risk factors for developing SAD, studies on depression suggest that those with diets low in certain nutrients, such as vitamin D and omega-3 fats, may be at greater risk for depression, and symptoms often improve when intake of these nutrients is increased. Additionally, individuals who eat a diet high in refined carbohydrates and/or lead a sedentary lifestyle may experience worse symptoms associated with SAD, especially weight gain, lack of energy, and fatigue.

What You Can Do:

While symptoms of SAD are generally minor for most, anyone who suffers from depression is advised to see their doctor to rule out any serious behavioral health issues. Studies have shown that light therapy (sitting next to a special light box which mimics the sun), is an effective treatment for SAD for many people. For those with more severe symptoms, your doctor may recommend an antidepressant or cognitive behavioral therapy. In addition, the following diet and lifestyle modifications may be helpful:

  • Increase your intake of omega-3 fats from salmon, sardines or other fatty fish, grass-fed beef, walnuts, flax seeds, soybeans, and enriched eggs. Omega-3 fatty acids play an important role in brain health. Although most studies examine their effect on mood disorders and other types of depression, several reviews of population studies, including those in Finland and Iceland, showed a negative association between fish eating and depression, including seasonal depression. In addition, researchers have found an association between lower plasma omega-3 levels and depression, and improvements in depression when subjects received supplemental doses.
  • Make sure you get adequate vitamin D by exposing your face and arms to sunlight for 10 minutes each day, eating fatty fish, eggs, and fortified milk, and taking a vitamin D supplement if necessary. Vitamin D plays many important roles in the body, and studies have found a negative association with depression. In a study that examined the effects of adding vitamin D to antidepressant treatment in subjects with major depressive disorder, researchers found that adding 1 500 international units (IU) of vitamin D to treatment was superior in treating depression. Although much research has established an association between low levels of vitamin D and higher likelihood of SAD, studies on the benefits of using vitamin D supplements alone to treat SAD have been inconsistent.
  • Eat a healthy, balanced diet that includes several servings of fruits, vegetables, whole grains, low fat dairy foods, fish, and lean proteins. Plant foods especially have beneficial nutrients and phytochemicals that may play a role in regulating mood, body, and brain health. In a review of 21 studies that compared dietary patterns to depression, Lei et al found that individuals with low intake of fruits and vegetables had higher odds of depression. The researchers also noted that although it has been difficult to establish the role of individual nutrients in preventing or treating depression, it may be possible that the various nutrients contributed by an overall “healthy diet” act synergistically to prevent depression.
  • Choose complex carbohydrates over refined carbs. One of the symptoms of SAD is an increased craving for carbohydrate foods. Unfortunately, filling up on sweets, pasta, and other refined carbohydrate foods causes a spike in blood glucose and insulin levels, and often leads to weight gain and fatigue. In addition, research from the Women’s Health Initiative found that higher glycemic index foods actually contribute to depression, especially in postmenopausal women. Choosing more high fiber, whole-grain carbohydrates such as oatmeal, brown rice, farro, or whole-wheat pastas helps to regulate glucose levels, and supplies a steady supply of lower calorie energy throughout the day.
  • Aim for exercise most days of the week. In addition to helping to prevent winter weight gain, regular aerobic exercise, for at least 30 minutes each day has been shown to improve mood and reduce both major depression and seasonal affective disorder. Exercising outside in sunlight has been shown to have even greater benefits.


Related Online CEU Courses:

Depression is a 1-hour online continuing education (CE/CEU) course that provides an overview to the various forms of depression, including signs and symptoms, co-existing conditions, causes, gender and age differences, and diagnosis and treatment options.

Nutrition in Mental Health is a 3-hour online continuing education (CE/CEU) course that discusses how good nutrition impacts a person’s mental health and well being.

Professional Development Resources is approved to offer continuing education by the American Psychological Association (APA); the National Board of Certified Counselors (NBCC); the Association of Social Work Boards (ASWB); the American Occupational Therapy Association (AOTA); the American Speech-Language-Hearing Association (ASHA); the Commission on Dietetic Registration (CDR); the Alabama State Board of Occupational Therapy; the Florida Boards of Social Work, Mental Health Counseling and Marriage and Family Therapy, Psychology & School Psychology, Dietetics & Nutrition, Speech-Language Pathology and Audiology, and Occupational Therapy Practice; the Ohio Counselor, Social Worker & MFT Board and Board of Speech-Language Pathology and Audiology; the South Carolina Board of Professional Counselors & MFTs; and by the Texas Board of Examiners of Marriage & Family Therapists and State Board of Social Worker Examiners.