A lack of energy, melancholy, decreased libido, weight gain, sleep disturbance, and slowed brain function are all symptoms of seasonal depression, also called seasonal affective disorder (SAD). To counteract these feelings, we're turning to light therapy this winter.

Suzanne Filion, a psychologist and author in Ottawa, Ont., walks us through how light affects the brain and how to choose the right therapy therapy device to help with seasonal depression.

How light affects mood

Researchers have long examined the healing power of light and developed a method to improve the physical and mental health of those struggling with SAD: light therapy.

Light is a source of life, warmth, energy and rejuvenation. In humans, light captured by the retina has a direct impact on the brain and its daily functions. When brightness is insufficient for the brain's needs, we often see signs of depression that we can link to an anomaly of circadian rhythms affected by brightness.

According to some experts, the fluctuation of hormones or the activity of certain neurotransmitters is even more pronounced when the amount of sunlight decreases, causing a decrease in the activity of serotonin, known to affect mood. Melatonin, a hormone linked to the sleep cycle, can also be affected. This can disrupt our quality of sleep and increase fatigue.

Studies have shown that light therapy can help counteract these feelings and changes.

Light therapy for women

The majority of people who suffer from SAD are women (for every one man, five women experience the disorder). Seasonal changes affect females much more than males after puberty, suggesting a link between depression and the secretion of estrogen and progesterone in females.

Specifically, there are receptors for sex hormones in the brain, and the varying responses of men and women to light deprivation in winter could result from different effects on these receptors.

In addition, brain hormones and neurotransmitters (melatonin, serotonin) and some ovarian hormones (progesterone, estrogen) play a key role in regulating the biological clock, which in turn influences circadian rhythms: libido, appetite, mood, sleep, concentration. Good light hygiene can seriously benefit you, not only during the slow weeks of winter, but throughout the year too.

How to use a light therapy device

When: First thing in the morning is usually best. To find the optimal time for your sleep schedule, take the AutoMEQ questionnaire.

Power: 10,000 lux

Distance: Usually between 30 and 45 cm from the eyes.

Duration: Start with 20 minutes in the morning, then increase in five to 10 minute increments to reach 45 minutes.

Protective screen: Make sure the lamp has a screen that filters UV rays.

Dimension of the luminous surface: The minimum dimension of a light therapy device should be 21.5 cm x 28 cm.

Gaze direction: It is best to look down with your eyes open. Do not look at the lamp; your eyes should be two-thirds lower than the top of the lamp.

Lamp positioning: Directly in front of you or to the side, about 45 degrees. The lamp should be elevated (preferably at eye level), and the top of the lamp is tilted slightly downward (tilt your head slightly down).

Frequency: For best results, stay consistent. When light therapy is stopped, symptoms usually do not return for a few days. Some people pause their treatment for one or two days—for example, over a weekend—without experiencing symptoms.

Duration and intensity: Increasing the duration of exposure is often more effective than increasing the intensity, but there are limits. Exposure to more than 90 minutes of light therapy per day is not recommended. The minimum intensity to obtain a certain antidepressant effect should be 1500 lux, which you can achieve either outdoors or indoors in a very well-lit room during the day. However, this dosage is considered too low, and therefore ineffective, in a clinical treatment of light therapy (for depression, for example). In this case, an intensity of 10,000 lux is recommended.

Location: Do your sessions in a calm and soothing place. The room must be sunny or illuminated: don't do light therapy in the dark.

Measuring lux inside and outside

Typical room at home: 100 to 200 lux

Well-lit room, with skylights or large windows: 800 to 1,500 lux

Cloudy or winter day outside: 1,500 to 5,000 lux

Light therapy lamp: 10,000 lux

Sunny summer day, around noon, outdoors: 50,000 to 100,000 lux 

Our top picks for light therapy devices

The market is flooded with gadgets—how do you know which one will work? There are lamps with surfaces that are too small, bases that are too short, and intensity that is too low. There is also a whole range of decorative lamps sold as light therapy devices. Here are are picks that have been proven to help with SAD:

Carex Day-Light Elite Light Therapy Lamp

BUY NOW

SUXIO Light Therapy Lamp

BUY NOW

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