For some people, changes in weather or the seasons, has no affect on their ability to cope with daily life. For others, however, the shorter days that come with Fall can trigger the beginning of a clinical depression that can last until Spring. This condition is called seasonal affective disorder -  SAD. It can be a debilitating condition. A person living with SAD may find it extremely diffcult to maintain their usual daily routine at work and at home.

A person living with SAD may find it extremely diffcult to maintain their usual daily routine at work and at home.

SAD was officially recognized as a disorder in the 1980s. As yet, there is no confirmed cause but the condition is thought to be related to seasonal variations in light. A biological internal clock in the brain regulates our daily rhythms. This biological clock responds to changes in season, partly because of differences in the length of the day.

For many thousands of years, the cycle of human life revolved around the daily cycle of light and dark. We were alert when the sun shone. We slept when our world was in darkness. Electricity allowed us to be productive any time of the day. But our biological clocks may still be telling our bodies to sleep as the days shorten. This puts us out of step with our daily schedules, which no longer change according to the seasons. Other research shows that neurotransmitters - chemical messengers in the brain that help regulate sleep, mood, and appetite - may be disturbed in someone with SAD.


SAD can be difficult to diagnose. Many of the symptoms are similar to those of other types of depression or bipolar disorder. Even physical conditions, such as thyroid problems, can present like depression. Generally, symptoms that recur for at least two consecutive winters, without any other explanation for the changes in mood and behaviour, indicate the presence of SAD.

Symptoms may include:

  •  changes in appetite, in particular a craving for sweet or starchy foods
  •  weight gain
  •  decreased energy
  •  fatigue
  •  tendency to oversleep
  •  difficulty concentrating
  •  irritability
  •  avoidance of social situations
  •  feelings of anxiety and despair

The symptoms of SAD generally disappear when spring arrives. For some people, this happens suddenly with a short time of heightened activity. For others, the effects of SAD gradually go away. Symptoms of summer depression may include poor appetite, weight loss and difficulty sleeping.

Research in Ontario suggests that between two per cent and three per cent of the general population may have SAD. Another 15 per cent have a less severe form of SAD described as the winter blues.

Generally, SAD is a condition affecting adults over the age of twenty. The condition is more common in woman than men.The risk of developing SAD decreases with age.

SAD seems to be more common in northern countries, where the winter day is shorter. Deprivation from natural sources of light is also of particular concern for shift workers. People with SAD find that spending time in a southerly location brings them relief from their symptoms.


There is effective treatment for SAD. Even people with severe symptoms can get rapid relief once they begin treatment. People with mild symptoms can benefit from spending more time outdoors during the day and by arranging their environments so that they receive maximum sunlight. Trim tree branches that block light, for example, and keep curtains open during the day. Move furniture so that you sit near a window. Installing skylights and adding lamps can also help.

The activity and increased exposure to natural light can raise your spirits.

Exercise relieves stress, builds energy and increases your mental and physical well-being. Build physical activity into your lifestyle before SAD symptoms take hold. If you exercise indoors, position yourself near a window. Make a habit of taking a daily noon-hour walk. The activity and increased exposure to natural light can raise your spirits.

A winter vacation in a sunny destination can also temporarily relieve SAD symptoms, although symptoms usually recur after you return to a northern climate. At home, work at resisting the carbohydrate and sleep cravings that come with SAD.

Many people with SAD respond well to exposure to bright, artificial light. Light therapy, involves sitting beside a special fluorescent light box for several minutes a day. A health care professional should be consulted before beginning light therapy.

For people who are more severely affected by SAD, antidepressant medications can be used in relieving symptoms. Counseling and therapy, especially short-term treatments such as cognitive-behavioural therapy, may also be helpful for winter depression.

Increasing your exposure to light, monitoring your diet, sleep patterns and exercise levels, are important first steps. For those who are severely affected, devising a treatment plan with a health care professional consisting of light therapy, medication and cognitive-behavioural therapy may also be needed.

Adapted from: The Canadian Mental Health Association.

For more information about SAD:

The Seasonal Affective Disorder Association

Mayo Clinic