Seasonal Affective Disorder

As the days grow shorter and sunlight becomes scarce, many individuals experience changes in mood, energy, and motivation. This often comes with increased fatigue, hunger, and cravings for carbohydrates and sugars. Here, in the PNW, daylight is in short supply; December 21st (the shortest day) has over 7 hours less sun than the year's longest day in June!

This shift is frequently linked to a disruption in your circadian rhythm—your body's internal clock that regulates energy, sleep, and appetite. Sunlight is the primary signal that keeps this clock on time. Reduced light exposure can throw it off balance, affecting key brain chemicals like melatonin.

The good news? You can reset your rhythm. Light therapy is a powerful, evidence-based treatment that uses a specialized light box to mimic natural sunlight. Its effects on seasonal depression can be as effective as antidepressant medication.

Brighten Your Mood, Naturally

A definitive 2024 study in JAMA Psychiatry has solidified what many clinicians have seen: light therapy is a powerful tool for fighting major depressive disorder, not just seasonal affective disorder (SAD).

The research, analyzing data from over 850 people, found that adding daily 10,000 lux light therapy sessions to a treatment plan dramatically improves outcomes.

The Key Findings:

• 41% of patients achieved full remission (vs. 23% without it)

• 60% saw significant symptom reduction (vs. 39%)

Beyond Seasonal Blues: New Research Confirms Light Therapy's Power for Major Depression

The therapy aims to reset your biological clock (circadian rhythm) and boost the production of serotonin, a neurotransmitter that affects mood. It may also help regulate melatonin, a hormone involved in sleep patterns.

How Does Light Therapy Work?

Benefits of Light Therapy

• Improves mood

• Enhances energy levels

• Helps regulate sleep patterns

• Can reduce symptoms of depression related to SAD and non-seasonal depression

Light Box: Use a light therapy box that emits 10,000 lux of full-spectrum light, which is much brighter than standard indoor lighting but not as bright as direct sunlight.

Timing: Light is good for mood, but only in the morning. Using the lightbox after 2:30pm can worsen mood by flipping the biological clock. Try to keep a regular sleep schedule and avoid staying up beyond 11pm.

Duration: Start with 20 to 30 minutes per day. You will need to sit directly under the lightbox for 1-2 hours a day to get the full effect.

Distance: The box should hover over your head at an angle (e.g. 45 degrees) just like the sun. Try to stay within 12 inches of the light, but don’t stare directly into it. You can read, eat, or use a laptop while under it but avoid staring directly into the light.

What month to start and end light therapy: Start the lightbox at least 2 weeks before you anticipate a seasonal dip in your mood. As the light increases in the spring, you can taper it down over 2 weeks by decreasing the time under the box (e.g. lowering by 15 minutes per week). The sudden increase in light in March can trigger mania and agitation in people with bipolar disorder, so they may need to stop the lightbox in February.

How to Use Light Therapy

Potential Side Effects & Precautions

• Eyestrain or headaches

• Nausea

• Irritability or agitation

• Insomnia (if used too late in the day)

These side effects are usually mild and often resolve with adjustments in duration or timing of exposure.

• Use with extreme caution if you are taking any medications that make you sensitive to light

• If you have eye conditions or are sensitive to light, please consult with your eye specialist prior to use

• People with bipolar disorder should use light therapy cautiously, as it can trigger manic episodes. If you believe this may be you, let's chat 1-on-1 about how we can incorporate this into your treatment.

Considerations

Intensity: at least 5,000 lux; 10,000 lux is optimal (need to use longer, 2 hours if 5,000 lux vs. 30-60 min for 10,000 lux)

Screen Size: at least 12 x 17 inches

Wavelength: around 509 nM (White Light)

UV Filter: Fluorescent lamps should be fitted with a diffusing screen that filters ultraviolet (UV) rays that can be harmful to the eyes and skin with long-term use of the device. Claims of UV protection are common, but questionable if a polycarbonate filter is not specified.

How to Chose a Light

Be careful here; most light boxes don't work. The top-selling products are small and attractive, but they aren't big enough to bring relief. Unfortunately, effective models are also spendy, making it a difficult market to navigate.

Here's how to shop for one:

Here are a few options: