As we are past the winter solstice – the shortest day of the year with a measly nine of sunlight in Chatham-Kent – many of us long for a therapeutic dose of sun exposure easily available during long days of summer.
Just as the dreary, dark days of winter peak for many so do feelings of melancholy, fatigue, and depression. Seasonal Affective Disorder, or SAD (its punny appropriate acronym) is estimated to affect 2-3% of the Canadian population, with another 10-20% experiencing “winter blues” – a less severe form of SAD.
SAD presents with symptoms similar to other depressive disorders – decreases in energy, irritability, oversleeping, and weight gain are all common. An individual experiencing depressive symptoms for two winters in a row, with no other underlying issues can be diagnosed with SAD.
The physiological cause of SAD is unclear, but decreased serotonin levels, vitamin D deficiency, and the disruption of circadian rhythm (the bodies internal clock) all have demonstrable links to development of wintertime depression.
All of these potential causes may be linked to light exposure. On exposure to light, the retina sends messages back to the hypothalamus – the area of the brain that regulates sleep-wake cycles, temperature, mood, and even sex drive.
Fortunately SAD is a highly treatable condition. Up to 85% of individuals benefit from bright light therapy – a simple therapy utilizing an artificial light box for two hours daily. Increased exposure to sunlight during the day, and a consistent sleeping schedule can also be helpful. Correction of Vitamin D deficiency has been shown to improve depression scores in individuals with SAD, and is a cheap, safe therapy with a number of other health benefits.
Feeling depressed in the winter months shouldn’t be considered normal – if you notice a mood change seasonally speak to your health-care provider. Increase your exercise, seek some light exposure, and consider vitamin D supplementation. Winter is part of being Canadian, but Seasonal Affective Disorder doesn’t have to be.