Back to Knowledge Center Results

Seasonal Affective Disorder

Seasonal Affective Disorder (SAD) is a type of depression that is triggered by changing seasons occurring in late fall or early winter and sometimes lingering in the spring and early summer seasons. The most common type is winter-onset depression. Individuals may feel moody, have no energy and unmotivated. While a specific cause is unknown, we do know that certain factors and causes may increase your risk of SAD.

Factors and Causes

  • Location. SAD is more significant among individuals who live far north or south of the equator where there is less sunlight during the winter and there are longer days during the summer.
  • Gender. Diagnosed more in women than in men.
  • Age. Younger individuals have a higher risk of winter SAD.
  • Family history. Individuals may be more likely to have relatives with SAD or other forms of depression.
  • Clinical depression or bipolar disorder. Symptoms may worsen if you have one of these conditions.
  • Biological clock. The reduced level of sunlight in the fall and winter may cause winter-onset SAD. The decreased sunlight may disrupt your body's internal clock and lead to feelings of depression.
  • Serotonin levels. A drop in serotonin (a brain chemical neurotransmitter) that affects mood might play a role because reduced sunlight can cause a drop in serotonin.
  • Melatonin levels. The change in season can disrupt the balance of the body's level of melatonin which plays a role in sleep patterns and mood.

What are the symptoms of SAD?

Symptoms of decreased interest in everyday activities, concentration, energy and appetite are common. Your body may feel heavy and your arms and legs may feel like lead. While the fall and winter seasons are most common, some individuals have an opposite pattern that begins in the spring or summer seasons and most have depression related symptoms as well. Either way, symptoms may start out mild and become more severe as the season progresses.

Depression Symptoms

  • Feeling depressed most of the day, nearly every day
  • Feeling hopeless or worthless
  • Having low energy
  • Losing interest in activities you once enjoyed
  • Having problems with sleeping
  • Experiencing changes in your appetite or weight
  • Feeling sluggish or agitated
  • Having difficulty concentrating
  • Having thoughts of death or suicide

Fall and Winter Symptoms

  • Irritability
  • Tiredness or low energy
  • Problems getting along with other people
  • Hypersensitivity to rejection
  • Heavy lead feeling in the arms or legs
  • Oversleeping
  • Appetite changes, craving for foods high in carbohydrates
  • Weight gain

Spring and Summer Symptoms

  • Depression
  • Trouble sleeping (insomnia)
  • Weight loss
  • Poor appetite
  • Agitation or anxiety

How is SAD treated?

Steps can be taken to help keep your mood and motivation throughout the year. Treatment may include light therapy, psychotherapy, medications or a combination of different treatments. Try taking a walk at work during breaks to get some sunlight every day to raise serotonin levels. It's normal to have days when you feel a little down but if you feel down for days at a time and you can't get motivated to do activities you normally enjoy, your sleep patterns and appetite have changed, you feel hopeless or think about suicide, consult with your physician.​

Internal Medicine