How Light Therapy Can Help You Manage Seasonal Affective Disorder (SAD) During the Winter Months
- Odile McKenzie, LCSW
- Dec 8, 2025
- 3 min read
As the weather gets colder and daylight becomes limited, many people begin to notice shifts in their energy, mood, and motivation. If you’ve been feeling heavier, more fatigued, or less like yourself lately, you may be experiencing Seasonal Affective Disorder (SAD), a form of depression triggered by shorter, darker days.
When sunlight feels scarce, one of the most effective and accessible tools we have is light therapy. It’s evidence-based, easy to use at home, and can make a meaningful difference in how you feel throughout the winter.
This guide walks you through what SAD is, why light therapy works, and exactly how to use it safely and effectively.
What Is Seasonal Affective Disorder (SAD)?
SAD is a seasonal pattern of depression that typically begins in late fall and continues through winter. The shorter days disrupt your biological rhythms:
Reduced sunlight lowers serotonin levels, affecting mood
Increased darkness boosts melatonin, making you feel tired
Your internal clock becomes dysregulated
These are physiological responses, not personal shortcomings. Light therapy supports your body in recalibrating.
What Is Light Therapy?
Light therapy involves sitting near a bright light box that emits 10,000 lux of light, much brighter than typical indoor lighting and designed to mimic natural sunlight.
Used consistently, it can:
Improve mood
Increase energy
Regulate sleep
Reduce cravings
Lessen overall seasonal symptoms
It is one of the most recommended treatments for SAD.
How To Use a Light Therapy Box (Step-by-Step Instructions)
1. Choose the Right Light Box
Look for:
10,000 lux brightness
UV-free light
A size large enough to illuminate your face
Avoid blue-light-only devices; they are not the standard treatment for SAD.
2. Use It in the Morning
Timing is key. For the best results:
Use the light within the first hour of waking
Sit about 16–24 inches away
Keep the light on for 20–30 minutes
Morning exposure helps reset your circadian rhythm and signals your brain that it’s daytime, even on dark winter mornings.
3. Do Not Stare Directly Into the Light
Place the light slightly to the side so it reaches your eyes indirectly. While using it, you can:
Journal
Read
Eat breakfast
Plan your day
Sit quietly and breathe
Think of it as recreating the experience of bright morning sunlight indoors.
4. Be Consistent for 2–4 Weeks
Many people begin to feel relief within 1–2 weeks, but full benefits often appear after about a month. Daily use throughout the winter is recommended for those with a predictable seasonal pattern.
5. Watch for Mild Side Effects
Light therapy is very safe, but can occasionally cause:
Headaches
Eye strain
Feeling overstimulated
If this happens, try reducing your session time or increasing your distance from the light.
6. Combine It With Other Winter Supports
Light therapy works best when paired with:
A consistent sleep routine
Medical guidance on Vitamin D levels
Think of your winter wellness plan as a combination of supports, not a single tool.
Who Should Consult a Doctor Before Starting?
Speak with a medical provider first if you:
Have bipolar disorder
Take medications that increase light sensitivity
Have eye conditions like glaucoma or retinal issues
This helps ensure safe and effective use.
A Therapist’s Closing Reflection
If winter feels heavy, it is not a sign of weakness. It is your body responding to real shifts in light, temperature, and rhythm. Light therapy is not about “fixing” you, it’s about supporting your biology so you can move through the season with more steadiness and ease.
You deserve to feel well, even during the darkest months of the year. If your mood feels overwhelming or difficult to manage, therapy can help you build deeper support, healthier coping patterns, and a sense of grounding through the winter.
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