Answers are grounded in this paper and cite their sources.
Differences in symptoms between seasonal and nonseasonal mood disorders provide some support for seasonal affective disorder as a diagnostic subtype of mood disorders. However, the genetic loading for mood disorders (of unspecified seasonality), as determined by the family history method, is similar for seasonal and nonseasonal mood disorders.
No takes yet. Share an insight, caveat, or question.
Allen et al. (1993) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: