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How not to be SAD this winter

Toronto, December 19, 2018

By Mary Dickie

A person's hands make a heart shape in front of a winter scene
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It’s not surprising that people like to light candles and put up sparkling lights at this time of year. With the winter solstice landing on Dec. 21, we are currently experiencing the shortest and darkest days of the year.

The lack of sunlight during the months of November, December and January can make many people feel blue, but a number of Canadians—about two per cent—experience the more intense symptoms of Seasonal Affective Disorder (SAD), characterized by fatigue, sadness, irritability and low energy. SAD is not considered a separate diagnostic entity but a sub type of mood disorder, with a recurring seasonal pattern. It’s associated with decreased levels of the neurotransmitter serotonin and increased levels of the hormone melatonin, both of which help to regulate the body’s circadian rhythm, or 24-hour clock.

“Everything within our body runs to a certain rhythm, and external light affects our inner circadian clock,” explains Dr. Venkat Bhat, a psychiatrist and fellow at the St. Michael’s Centre for Depression and Suicide Studies.

“When daylight gets shorter in the winter, most people’s internal clocks adjust, with a 24-hour pattern which we seem to observe whether the days get longer or shorter. But some people are not able to do that.”

The resulting drop in serotonin levels can lead to feelings of sadness and lethargy, he adds.

“What’s interesting is that most people don’t even know that SAD exists until we start asking detailed questions about their symptoms and they say ‘Yes, I’ve noticed that,’” says Dr. Bhat. “We try to see how severe it is—is it just having the blues, or is it so bad that you are unable to function? And depending on that, we suggest treatments.”

There are three main treatments for SAD: light therapy, antidepressant medications and cognitive behavioural therapy. Regular exposure to a lightbox that emits full-spectrum light similar to sunlight has been found to be effective, although it takes a couple of weeks to make an impact. So Dr. Bhat recommends starting the treatment early.

“If people know it’s coming, they can start light therapy two to four weeks before the beginning of December, for instance. And if they know that by the end of March they’ll be better, they can stop using the light a few weeks after that,” he says.

Light therapy, administered preferably in the morning for 30 minutes, is well tolerated with only minor side effects.

“Light exposure creates nerve impulses that go along the retinal nerve to the back of your head, causing the regulation of melatonin release, and melatonin resets your 24-hour clock,” Dr. Bhat says. “If it’s mild SAD, we would maybe only suggest light therapy, but if it’s more serious, we would likely also use pharmacological therapy or cognitive therapy. And we also suggest lifestyle changes.”

These can include dawn simulation—using a device that emits a low level of light that gradually increases to room light level prior to awakening— getting outside more, exercising more, adopting a regular sleep-wake cycle, avoiding substance use and alcohol, and going south.

“That’s not feasible for everyone,” Dr. Bhat acknowledges about that last recommendation. “In general we emphasize stress management, spending more time outside and exercising, which we recommend to everyone who has anxiety or depressive disorders.”

About St. Michael's Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 29 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.

About Unity Health Toronto

Unity Health Toronto, comprised of Providence Healthcare, St. Joseph’s Health Centre and St. Michael’s Hospital, works to advance the health of everyone in our urban communities and beyond. Our health network serves patients, residents and clients across the full spectrum of care, spanning primary care, secondary community care, tertiary and quaternary care services to post-acute through rehabilitation, palliative care and long-term care, while investing in world-class research and education. For more information, visit

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