Seasonal Affective Disorder

Overview

Seasonal Affective Disorder (SAD) is a mood disorder characterized by recurrent episodes of depression at times of seasonal change. It is most common in late fall and winter when there is less daylight. As many as a million Canadians suffer from this although many more perceive a tendency to low moods in the winter months. SAD affects people of all ages although it occurs more often in women usually beginning in their twenties.

Causes

Research into the causes of SAD is ongoing. However scientists believe it is related to seasonal changes in our exposure to daylight. A "biological internal clock" in the brain regulates our circadian (daily) rhythms and the production of neurotransmitters that affect our sleep mood and appetite. When we were hunters and gatherers the sun controlled our activities. We were active when the sun shone and we slept when it set. In our modern society the sun no longer controls our activities. We go to work when it is dark and arrive home at night long after the sun has set. We work indoors with poor lighting and hardly ever venture into real sunlight. While we no longer follow the sun our internal biological clocks may still be telling our bodies to sleep more as the days shorten. This internal clock puts our body out of step with our daily work schedules and family life.

Melatonin a sleep-related hormone secreted by the pineal gland in the brain has been linked to SAD. This hormone which may cause symptoms of depression is produced at increased levels in the dark. Therefore when the days are shorter and darker the production of this hormone increases.

Symptoms

SAD can be difficult to diagnose until a pattern is recognized since many of the symptoms are similar to those of other types of depression. As well it is sometimes misdiagnosed as hypothyroidism hypoglycemia infectious mononucleosis and other viral infections.

Many people feel like "hibernating" as winter approaches. They find themselves eating more and sleeping longer. This is normal human behavior. But for people with SAD the symptoms are much more severe. SAD is a true depressive illness and can disrupt a person's daily life.

Symptoms may include:

  • Changes in appetite
  • Craving for sweet or starchy foods
  • Weight gain
  • Decreased energy
  • Fatigue
  • Tendency to oversleep
  • Difficulty concentrating
  • Irritability
  • Feelings of anxiety and despair
  • Thoughts of death and suicide
  • The depression is often worst in the evening.

The symptoms of SAD generally occur between the months of October and April. Some people will be affected for this entire period. Others may only notice a change for a couple of weeks or a month. There is also a kind of "reverse SAD" in which some people experience seasonal depression in the summer rather than winter possibly in response to high heat and humidity. During this period the depression is more likely to be characterized by insomnia decreased appetite weight loss and agitation or anxiety. Some people find relief with summer trips to cooler climates. Generally normal air conditioning is not sufficient to relieve this depression and an antidepressant may be needed. In still fewer cases a patient may experience both winter and summer depressions while feeling fine in the fall and spring.

It is important to seek medical treatment if your symptoms have occurred at a certain time of the year for at least two consecutive years. With the caveats outlined above most people with SAD report clearly improved mood in the spring and summer.

Treatment

Many of us find ourselves with lower energy and mood during the fall and winter. We would benefit from spending more time outdoors during the day by arranging our environments so that they receive more natural light and by taking better care of our physical needs.

  • Take a ·light break' instead of a coffee break.
  • Move your furniture so that you sit near a window.
  • Installing full-spectrum bulbs in lamps and light fixtures can also help.
  • Take care of your physical needs by eating properly and getting sufficient sleep to raise your energy level and buffer your mood.

If you experience the more severe symptoms associated with SAD for more than a couple of weeks during autumn and/or winter you should seek professional help especially if you find yourself thinking about death and suicide.

Many people with Seasonal Affective Disorder respond well to exposure to bright artificial light. A high fidelity light source of 10000 LUX works by providing daylight balanced soothing glare-free light in a concentrated "dose" which affects the hormones and neurotransmitters involved in SAD. "Phototherapy" or light therapy is about 10 to 20 times brighter than the average office and involves sitting beside this special light box for about 30 minutes a day. Within a couple of weeks 70% of those with SAD experience a noticeable reduction in their symptoms. As with any medical procedure a health care professional should be consulted before beginning light therapy.

Increasing your exposure to light monitoring your diet sleep patterns and exercise levels are important first steps in maintaining your health and regulating your circadian rhythms. For those who are severely affected by SAD devising a treatment plan with a health care professional including light therapy medication and/or therapy may help to relieve these depressive symptoms.

Additional Resources:

Mood Disorders Association of Ontario

University of British Columbia SAD Info Page

Canadian Network for Mood and Anxiety Treatments

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Written by Webmaster Monday, 08 March 2010 20:27