Actigraphy and SIGH-SAD are the gold standards.

Actigraphy and the SIGH-SAD rating scale are your best bets for objectively tracking late-winter SAD severity and treatment response over weeks.

Actigraphy (a wrist-worn motion sensor) gives you objective sleep/wake data – total sleep time, wake after sleep onset, timing. That’s huge because SAD messes with circadian rhythms and sleep architecture. It’s passive, doesn’t rely on memory, and you can see week-over-week trends. Doctors often use it alongside a sleep log for context, but the actigraph itself is the hard data.

The SIGH-SAD is a clinician-rated interview that combines the standard Hamilton Depression Rating Scale with an addendum for atypical symptoms (hypersomnia, carb cravings, leaden paralysis). That’s critical because typical depression scales miss the atypical features that dominate winter SAD. A weekly SIGH-SAD gives you a clear severity score and response trajectory. Unlike a self-report questionnaire, it reduces placebo effect and recall bias.

Sleep logs are subjective but cheap – fine as a supplement, not a replacement. If you can only do one, go with the SIGH-SAD for severity and actigraphy for behavior.

Pick one objective measure, run it consistently, and you’ll actually know if treatment is working.