Seasonal Depression Test: A Step-by-Step Walkthrough
When the days get shorter and your mood crashes every November, something more specific than "winter blues" may be happening. A targeted seasonal depression test can tell you whether you're dealing with Seasonal Affective Disorder (SAD) - not just low energy - and exactly what to do about it.
Standard depression screeners miss the most important part of SAD: the pattern. According to the National Institute of Mental Health (NIMH), SAD is a subtype of major depression that follows a predictable seasonal cycle. That cycle is what sets it apart - and what most quick online quizzes fail to capture.
What follows is the two-screener process used in clinical practice: what to fill out, what your scores actually mean, and which next step fits your results.
Why a General Depression Test Is Not Enough
The PHQ-9 is the most widely used depression screener in primary care. It measures how severe your symptoms are right now. But it has no seasonal component at all.
A PHQ-9 score of 12 in January tells a clinician you have moderate depression. It does not tell them whether you score a 2 in July. That contrast - the seasonal swing - is exactly what diagnoses SAD.
The right tool for seasonal screening is the Seasonal Pattern Assessment Questionnaire (SPAQ). Developed by SAD researcher Norman Rosenthal and colleagues, the SPAQ asks how much your mood, sleep, energy, appetite, weight, and social activity change across different months of the year. It captures the pattern, not just the snapshot.
The complete picture comes from using both: PHQ-9 for symptom severity, SPAQ for seasonal pattern. Neither alone is sufficient.
Step-by-Step: How to Test Yourself for Seasonal Depression
Step 1 - Choose the Right Time to Test
Timing matters more for SAD screening than for any other depression test. You need to test during your suspected low season to get meaningful scores.
- Winter SAD: Test between November and February for peak symptom scores.
- Summer SAD (less common): Test between June and August.
- Retest in your high season (typically May-August for winter SAD) to confirm the contrast.
Testing in the middle of summer when you feel fine will produce scores that look normal. That's not a false negative - it's actually diagnostic evidence. But you need both data points to see the full picture.
Step 2 - Complete a General Depression Screener First
Start with the PHQ-9. Answer based on how you have felt over the past two weeks. This establishes your current symptom severity.
Score ranges work like this:
| PHQ-9 Score | Severity |
|---|---|
| 0-4 | Minimal or none |
| 5-9 | Mild |
| 10-14 | Moderate |
| 15-19 | Moderately severe |
| 20-27 | Severe |
Write down your score and the date. You'll compare this to your off-season retest later.
Step 3 - Complete the SPAQ for Seasonal Pattern
Next, complete the Seasonal Pattern Assessment Questionnaire. The SPAQ asks you to rate how much six areas of your life change by season: sleep length, social activity, mood, weight, appetite, and energy level.
Each area is rated from 0 (no change) to 4 (extremely changeable). Your total Global Seasonality Score (GSS) summarizes the overall seasonal impact.
The Center for Environmental Therapeutics (CET) offers free online versions of both the SPAQ and the AutoMEQ chronotype assessment. The AutoMEQ matters here: your circadian type - whether you are a morning or evening person - affects when light therapy works best.
According to CET, a GSS of 11 or higher, combined with a "problem" rating of moderate or severe, suggests clinically significant seasonal variation. Keep that score alongside your PHQ-9 result.
Step 4 - Apply the Diagnostic Thresholds
Not every seasonal mood dip is full SAD. The clinical distinction matters because it changes your treatment path.
Full SAD (based on Rosenthal SAD criteria, recognized by NIMH) requires:
- At least two consecutive years of seasonal depressive episodes
- Full remission (or a switch to hypomania/mania) in the opposite season
- Symptoms that impair daily functioning - work, relationships, or basic self-care
- Seasonal episodes that outnumber non-seasonal episodes across your lifetime
Subsyndromal SAD (sometimes called "winter blues") involves real symptoms that follow a seasonal pattern but do not reach full impairment levels. It is more common than full SAD and still responds well to treatment.
Ask yourself: Do my symptoms get in the way of daily life for weeks at a time? Have I seen this same cycle two winters in a row? If yes to both, full SAD is more likely.
Step 5 - Map Your Results to a Next Step
Your PHQ-9 score plus your SPAQ pattern together point toward a specific action level:
Mild (PHQ-9 5-9, GSS elevated)
Start with light therapy. Consistent morning use of a 10,000-lux lamp for 20-30 minutes is often the first-line recommendation. Get your vitamin D level tested with a simple blood draw.
Moderate (PHQ-9 10-14, GSS elevated)
Light therapy plus CBT-SAD - a structured version of cognitive behavioral therapy adapted for seasonal depression - may be more effective than either treatment alone. The Society for Light Treatment and Biological Rhythms (SLTBR) recognizes this combination as a well-supported clinical approach.
Severe or Multi-Year (PHQ-9 15+, confirmed SAD for 2+ years)
Talk to a prescriber. Bupropion XL (Wellbutrin XL) is the only FDA-approved medication specifically indicated for SAD prevention. It is typically started in the fall, before symptoms begin, rather than after they arrive.
Common Mistakes When Screening for Seasonal Depression
Most inaccurate SAD screens come down to the same handful of errors. They are easy to avoid once you know what to watch for.
Testing in the Wrong Season
This is the most common error. Complete the PHQ-9 in July and your baseline mood may look perfectly normal - even if January is miserable for you. Test during your suspected low season for the most meaningful score.
Confusing Grief or Life Stress With Seasonal Cycles
A bad November that follows a job loss, breakup, or major stressor is not SAD. SAD is defined by a pattern that repeats independently of life circumstances. If you can point to a clear external reason for last winter's low mood, that weakens the SAD hypothesis. Two or more cycles with no major stressor attached is stronger evidence.
Not Tracking Onset and Offset Dates
The SPAQ asks which months feel worst - but memory is unreliable. For a more accurate picture, keep a brief daily mood log (1-10 scale) for at least one full seasonal cycle. Note when you start feeling worse and when you start feeling better. Precise dates across two years are stronger diagnostic evidence than recalled impressions.
Skipping the Chronotype Step
Your circadian type affects both the severity of SAD and the optimal timing for light therapy. According to the Center for Environmental Therapeutics, the AutoMEQ assessment helps determine whether you should use your light lamp at 7am, 8am, or later. Using light at the wrong time can reduce its effectiveness or cause side effects like headache or agitation.
Treating a Positive Screen as a Diagnosis
A self-assessment is a starting point, not a clinical verdict. A positive SPAQ screen is a signal to seek professional evaluation - not a confirmed diagnosis. Many conditions can mimic SAD, including hypothyroidism, low vitamin D, and sleep disorders.
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What to Do After Your Screening
A positive screen gives you something concrete to bring to a clinician. Take your PHQ-9 score, your SPAQ Global Seasonality Score, and any symptom onset and offset dates you tracked. Together, those numbers give a provider a real foundation for evaluation.
For more context on interpreting severity scores, see our general depression test guide or the PHQ-9 walkthrough.
Light therapy, CBT-SAD, vitamin D supplementation, and - when needed - bupropion XL are all evidence-supported options. Most people with mild-to-moderate SAD see meaningful improvement with light therapy alone when it is started early, used consistently, and timed correctly for their chronotype.
The seasonal pattern that makes SAD harder to diagnose also makes it more predictable to treat. You know it's coming. That gives you time to prepare.
Frequently Asked Questions
Can I use the regular PHQ-9 to test for seasonal depression, or do I need a different tool?
The PHQ-9 measures how severe your symptoms are right now, but it has no seasonal pattern component. A score of 13 in January looks the same as a score of 13 in March - the PHQ-9 cannot tell the difference. To screen for SAD, pair the PHQ-9 with the Seasonal Pattern Assessment Questionnaire (SPAQ) or the free online SAD screener from the Center for Environmental Therapeutics. The PHQ-9 tells you how bad things are. The SPAQ tells you whether those bad stretches follow a predictable seasonal cycle. You need both for a complete picture.
What time of year should I take a seasonal depression test to get accurate results?
Test during your suspected low season for the highest-scoring, most meaningful results. For winter SAD, that typically means November through February. For the less common summer SAD pattern, test between June and August. Then retest in the opposite season to confirm the contrast. A score that drops dramatically from winter to summer is stronger evidence for SAD than a single snapshot. Mid-cycle testing - say, October before symptoms fully arrive - tends to underestimate severity. Waiting until you are in the thick of your low season gives you the clearest signal.
My score suggests SAD - does that mean I need antidepressants, or is light therapy enough?
Mild-to-moderate SAD often responds well to light therapy alone when used consistently - 10,000 lux for 20-30 minutes each morning, timed to your chronotype. According to the Society for Light Treatment and Biological Rhythms (SLTBR), light therapy is a well-established first-line option. Moderate-to-severe cases, or SAD that has recurred for three or more years, may benefit from adding CBT-SAD or consulting a prescriber about bupropion XL - the only FDA-approved medication for SAD prevention. Your PHQ-9 score severity is a reasonable guide: scores under 15 often respond to light therapy, while scores of 15 or higher warrant a provider conversation.
What is the difference between SAD and subsyndromal SAD (winter blues)?
Full SAD requires at least two consecutive years of seasonal depressive episodes that impair daily functioning and remit fully in the opposite season. Subsyndromal SAD - often called winter blues - involves real, recurring seasonal symptoms that do not reach the threshold of significant impairment. Both are genuine and both respond to similar treatments. The distinction matters mainly for treatment intensity. Winter blues may improve with a regular walk outside each morning or a modest light therapy routine. Full SAD, especially multi-year cases, is more likely to need structured treatment like CBT-SAD or medication.
Can summer SAD exist, and how is it different from winter SAD?
Yes. A smaller percentage of people with SAD follow a summer pattern instead of a winter one. Summer SAD symptoms often include insomnia rather than oversleeping, decreased appetite and weight loss rather than carbohydrate cravings, and agitation rather than fatigue. The SPAQ captures both patterns by asking about change across all seasons, not just winter. According to NIMH, summer SAD is less common but still follows the same two-year, functionally impairing cycle required for diagnosis. Treatment differs too - cool environments, reduced light exposure, and careful medication management replace light therapy as the primary tools.
How do I know if my vitamin D level is contributing to my seasonal symptoms?
Low vitamin D is common in winter, especially at northern latitudes, and some research links low levels to depressive symptoms. However, vitamin D deficiency and SAD are not the same thing and do not always co-occur. The only way to know your level is a blood test - typically a 25-hydroxyvitamin D serum test ordered by a primary care provider. If your level is low, supplementation may help with fatigue and mood. But vitamin D alone is not a SAD treatment. Think of it as a supporting step alongside your main SAD management plan, not a replacement for light therapy or professional evaluation.
Researched and written by Lisa Anderson at depression tests. Our editorial team reviews depression tests to help readers make informed decisions. About our editorial process.