In the past two weeks, a couple of patients told me something similar: their mood felt “off,” even though nothing stressful was happening in their lives.
One patient noticed she felt more tired after the time change. The sun set earlier, and her body slowed down. Even though she still did her chores and met her responsibilities, she caught herself calling it “laziness.” Together, we talked about how this feeling was real, but the label didn’t match the facts. Sometimes our bodies get tired earlier because of changes in sunlight, not because we’re doing anything wrong.
Another patient shared that he recently felt more distracted, unsure of himself, and unusually emotional. His work and home life were steady, yet he found himself searching for explanations—Why do I feel this way? Did something go wrong? We discussed how the mind often tries to “fill in the blanks” when mood changes, even if nothing in life has changed. Sometimes the cause is biological, not personal.
In both cases, I explained that many people notice mood shifts when the seasons change. This experience is common, and it doesn’t mean they are failing or losing progress. It simply means their bodies and brains are responding to the environment.
This is where Seasonal Affective Disorder (SAD) becomes important to understand.
What Is Seasonal Affective Disorder?
Seasonal Affective Disorder, or SAD, is a type of depression that follows a pattern based on the seasons. Most people think SAD only happens in winter, but research shows it can happen in any season—winter, spring, summer, or fall—depending on the person (American Psychiatric Association, 2022).
- About 1–5% of adults experience SAD each year.
- Up to 20% experience a milder form often called the “winter blues” (Melrose, 2015).
Scientists explain SAD using a few key ideas:
- Less Sunlight = Body Clock Changes
When daylight hours shrink, our internal clock can get out of rhythm. Research shows that light is the main signal that resets the brain’s “master clock,” which helps control sleep, mood, and energy (Czeisler & Gooley, 2007).
Without enough morning light, we may feel tired, foggy, or low in mood. - Serotonin Levels Drop
Serotonin helps regulate mood. Darker days can lower serotonin activity. - More Melatonin
Longer darkness can cause the body to release more melatonin, leading to sluggishness.
Is It Always Winter-Related?
Not always. Some people have summer-pattern SAD, where too much heat or sunlight affects sleep and mood (Rosen et al., 1990).
Research supports several treatments:
- Light therapy using a special lamp (Lam et al., 2006).
- Cognitive-behavioral therapy made for SAD (CBT-SAD).
- Vitamin D, though results are mixed and should only be taken with medical guidance (Gloth, Alam, & Hollis, 1999).
How You Can Support Your Mood
During Winter
Here are simple, research-supported steps you can take:
1. Notice Your Seasonal Pattern
Pay attention each year:
- Do you feel more tired or discouraged during winter?
- Do earlier sunsets affect your energy?
- Do you assume low energy means something is “wrong”?
Awareness helps prevent negative self-talk.
2. Get Sunlight in the Morning
Your brain needs light to reset its internal clock—this is backed by circadian rhythm research showing that morning light helps regulate mood and energy (Czeisler & Gooley, 2007).
Try:
- 5–10 minutes of morning sunlight
- Going outdoors soon after waking
- Sitting near a window if outdoor time isn’t possible
This is something both of my patients found helpful once they tried it.
3. Move Your Body
Exercise boosts mood and energy.
You don’t need an intense routine—start with:
- A short walk
- Light stretching
- A few minutes of strength work
Consistency matters more than intensity.
4. Stay Connected
Winter and the holidays can make people feel lonely.
Try to maintain simple connections:
- A weekly check-in
- A walk with a friend
- Time with supportive people
Connection protects emotional health.
5. Talk With a Doctor About Vitamin D
Low Vitamin D may affect mood for some people, but the research is mixed.
Because supplements can be overused, talk with a medical provider before taking any (Gloth et al., 1999).
6. Be Kind to Yourself When Energy Drops
Feeling tired does not mean you are failing.
Sometimes your body is reacting to the season.
Before blaming yourself, consider whether winter changes might be influencing your mood.
7. Prepare for Your Harder Months
If you notice a yearly pattern, plan ahead:
- Start light therapy early
- Lower unnecessary commitments
- Build in more rest
- Strengthen routines that help you feel grounded
Planning gives you control before mood shifts begin.
Seasonal mood changes are normal and very common. They do not mean you are weak, lazy, or doing something wrong. Our bodies respond to sunlight, temperature, sleep changes, and rhythm shifts. When you understand this, you can replace self-blame with self-care. And as we saw in both therapy sessions, awareness helps people feel more hopeful and less confused about their emotional experiences.
References
American Psychiatric Association. (2022). Diagnostic and statistical manual of mental disorders (5th ed., text rev.).
Czeisler, C. A., & Gooley, J. J. (2007). Sleep and circadian rhythms in humans. Cold Spring Harbor Symposia on Quantitative Biology, 72, 579–597.
Gloth, F. M., Alam, W., & Hollis, B. (1999). Vitamin D vs broad spectrum phototherapy in the treatment of Seasonal Affective Disorder. Journal of Nutrition, Health & Aging, 3(1), 5–7.
Lam, R. W., Levitt, A. J., Levitan, R. D., Enns, M. W., Morehouse, R., Michalak, E. E., & Tam, E. M. (2006). The Can-SAD study: A randomized controlled trial of bright light therapy and fluoxetine in Seasonal Affective Disorder. American Journal of Psychiatry, 163(5), 805–812.
Melrose, S. (2015). Seasonal Affective Disorder: An overview of assessment and treatment approaches. Depression Research and Treatment, 2015, 1–6.
Rohan, K. J., Sigmon, S. T., & Dorhofer, D. M. (2003). Cognitive-behavioral factors in Seasonal Affective Disorder. Journal of Consulting and Clinical Psychology, 71(5), 993–1004.
Rosen, L. N., Targum, S. D., Terman, M., Bryant, M. J., Hoffman, H., Kasper, S. F., & Wehr, T. A. (1990). Prevalence of Seasonal Affective Disorder at four latitudes. Psychiatry Research, 31(2), 131–144.*