SAD – more than just the winter blues

Carly has a bad breakup in October and, a month later, she loses her job. Soon after, her appetite starts to change, she stops socializing with friends and begins to feel worthless. In December, the 25-year-old is referred to St. Michael’s Centre for Depression and Suicide Studies for moderate to severe depression. When her psychiatrist begins asking questions, he discovers that she’s gained weight and is sleeping all the time.  

This isn’t the first time Carly has felt this way when the long dark days of winter set in. She is dealing with much more than a simple case of the blues. She is, in fact, experiencing the more intense symptoms of Seasonal Affective Disorder (SAD).   

Depression is the leading cause of disability worldwide. SAD (winter type) is a type of depression that typically develops in the fall, continues into the winter months and starts to diminish as the sunny days of spring reemerge. This recurring seasonal pattern, characterized by fatigue, sadness, irritability and low energy, affects about two per cent of Canadians.

There are several hypotheses about why SAD happens. Some experts believe the reduced level of sunlight disturbs our biological clocks or circadian rhythms, causing feelings of depression.

“External light appears to be a timekeeper for the body, so when the days begin to get shorter during the winter months, most people can adjust and it doesn’t have an impact on their 24-hour cycle. But for some people this isn’t the case,” says Dr. Venkat Bhat, a psychiatrist and fellow at St. Michael’s Centre for Depression and Suicide Studies – a centre uniquely positioned to tackle prevalent and interconnected mental health challenges.

A number of experts, including Dr. Bhat, say the eyes might be complicit.  Under normal circumstances, the retina’s sensitivity to light increases in the fall as light levels diminish.  People with SAD could have decreased retinal sensitivity to light leading to an altered 24-hour circadian clock. The altered body rhythms may lead to a dysregulation of neurotransmitters, including an imbalance of serotonin and melatonin in the brain. Patients with a family history of SAD and other forms of depression are at greater risk.   

On the bright side, there are treatments that can help. Light therapy, antidepressants and psychotherapy can be useful, depending on the severity of the case.  

Light therapy involves regular exposure to a light box that emits light similar to sunlight. “A lot of people show good response to light therapy,” says Dr. Bhat. “For people with recurring SAD, we suggest they start light therapy two to three weeks before they know the symptoms are going to start.”

Dawn simulators emit a less intense white light and can also play a valuable role in the treatment of SAD.  They expose sleepers to a slowly increasing intensity of light for 30 minutes or more before awakening.

Lifestyle changes can also help patients beat “the blues.” Dr. Bhat recommends proper sleep, daily walks outside, aerobic exercise and additional indoor lighting at home.  

If you think you may be experiencing SAD, remember it’s never too late to ask for help. Speak with a friend, family or your doctor.

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