SPAQ won’t tell you severity—use BDI-II or PHQ-9

The Seasonal Pattern Assessment Questionnaire is for screening and identifying seasonal patterns, not for tracking how bad someone’s SAD is right now. It asks about typical reactions to seasons, not current symptoms. So you wouldn’t use it to monitor severity in late winter.

For severity monitoring, you want a standard depression measure that can be repeated over time. The Beck Depression Inventory-II and the Patient Health Questionnaire-9 are both well-validated in seasonal affective disorder and widely used in clinical trials. They’re self-report, take a few minutes, and track changes reliably.

There is also the SIGH-SAD, which is the gold standard—but it’s a clinician interview, not self-report. For self-report, just stick with BDI-II or PHQ-9. Either will do the job.

The SPAQ is useful for initial assessment. Use it once. Then switch to something that measures severity.