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What is Seasonal Affective Disorder?

For many people, the dark and short days in the winter cause a general worsening of mental health. This phenomena is commonly known as SAD or seasonal depression.

Common symptoms include lower moods and energy levels, leading to poor sleep routines, impacted sociability, and lowered productivity. These symptoms affect different people to varying degrees; on the more severe end, it is termed seasonal affective disorder (SAD), while for milder levels of symptom severity it is referred to as seasonality by medical professionals.

Understanding SAD

SAD is triggered by the lack of natural sunlight exposure in the winter season due to the proven role of sunlight in serotonin production. To be more specific, bright light entering your eyes stimulates certain areas of the retina, playing a key role in serotonin production. Staying indoors and not getting sufficient bright light in the winter season also has the effect of signaling the pineal gland in your brain to ramp up melatonin production, making you feel more fatigued as melatonin is the hormone used to regulate your sleep-wake cycle and is generally activated in the night.


The role that bright light exposure has on serotonin, melatonin and the circadian rhythm explain the symptoms of SAD (and seasonality), as well as the importance of light.


Treating SAD

The foremost treatment for improving mental health during the winter is bright light therapy. The general recommendation for light therapy is through 10,000 Lux light, where Lux is the unit of measurement for light intensity and a standard desk lamp emits light that is <500 Lux. Light therapy has been proven to have similar effects to natural sunlight, promoting serotonin production while regulating melatonin levels, therefore improving mood and energy.

Additional lifestyle modifications have been shown to have a direct link with mental health and SAD, including sleep quality and physical activity. Gained benefits include better calibrated circadian rhythm, improved mood, energy and productivity levels. 

For more serious cases of the disorder, medication and therapy may be required to fully alleviate symptoms.

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