SAD and Your Eyes
Most often, people’s moods are affected by changes in the weather. A sunny, bright day can have us feeling happy, energetic and upbeat, while a cold, dark day can have us feeling “under the weather.” While these changes are noticeable, they do not usually affect our daily routine. That is unless you suffer from seasonal affective disorder, or SAD.
SAD is a type of depression that tends to occur (and recur) as the days grow shorter in the fall and winter.
SAD affects about two to three per cent of the Canadian population. While SAD can affect some children and teenagers, it is most common in people between 20 and 50 years of age, particularly women.
- Low mood
- Reduced interest in normally pleasurable activities
- Decreased concentration
- Oversleeping (often an increase of four hours or more each day)
- Low energy and fatigue
What Causes SAD?
The precise cause of SAD isn’t known, but genetics and age may be factors. Most evidence suggests that it arises from abnormalities in how your body manages its internal clock. Although our bodies are built with an internal clock that keeps us in sync with night and day, this clock is not always precise and relies on the intensity of sunlight to provide adjusting cues. These cues originate in the retina, located in the back of the eye, creating signals which pass through the optic nerve to the mid-brain, activating a number of chemical changes in the body.
One of these changes is the regulation and suppression of the hormone melatonin. Melatonin helps control body temperature, hormone secretion and sleep, and is thought to play a major role in SAD. Melatonin is produced in a specific area of your brain during the hours of darkness. During the low-light months of fall and winter, people with SAD produce more melatonin than normal – enough to cause symptoms of depression.
How is SAD Treated?
In many cases, the treatment of SAD is similar to that of other major depressive episodes. People affected may use antidepressants, mood stabilizing medication and/or psychotherapy.
The most common form of treatment is bright light therapy. In bright light therapy a light box – a small, portable device that contains fluorescent bulbs or tubes – is placed in front of the patient for certain periods of time throughout the day. Exposure to bright light, such as that from a light box, can suppress the brain’s production of melatonin, which helps regulate your body’s internal clock and reduce symptoms of SAD.
The light box gives off a type of light that isn’t found in normal household lighting, but rather lighting equivalent to that of a clear spring day.
The light is registered by the eyes through the retina, which then transfers impulses to the brain to normalize the body clock function. The light box should be placed so that the light does not shine directly into the eyes. The eyes need to be open and sunglasses should not be worn. Patients should not look directly into the light box because it can damage your eyes.
Main side effects of light therapy include irritability, agitation and eye strain. Consult a medical doctor before beginning light therapy.
Can Bright Light Therapy Damage My Eyes?
Ophthalmology researchers have expressed concern that bright light therapy may cause further damage to people who have pre-existing eye conditions such as glaucoma, cataracts or diabetic retinopathy, or who are using medications that cause light sensitivity.
Older people should also be wary of light therapy. As people age, they become more vulnerable to light-induced damage to the retinal tissue – increasing the risk of retinal damage and blindness.
If you have any of these risk factors, it is recommended that you consult your eye doctor before undergoing treatment.
For further information about seasonal affective disorder, contact a community organization like the Canadian Mental Health Association to find out about support and resources near you.