P071 Darkness metaphors for depression: a case of non-visual photoreception?

Abstract Darkness metaphors for depression appear cross-culturally and historically, from Japanese kurai (meaning both depressed mood and physical darkness) to Greek melaina chole (“black bile”) and Mesopotamian tādirtu (melancholy and darkness). We propose these metaphors stem from a neurobiological basis: individuals currently experiencing depression show impaired non-visual photoreception, unlike those with remitted depression who maintain normal non-visual photic sensitivity. Impaired light sensitivity during depressive states may form a neurobiological basis for experiencing depression as “darkness”. A global online survey (July 2020-February 2021) captured free-text depression descriptions from participants with diagnosed or suspected depression (n = 488) who completed standardised the DASS-21 and questionnaires. Thematic analysis revealed five major metaphor categories: darkness, weight, descent, entrapment, and container metaphors. We examined the relationships between three common depression metaphors and depression severity. Our findings show that darkness language uniquely predicts extremely severe depression (OR = 2.50), while descent and weight metaphors show no such relationship despite being equally common depression metaphors. The specific relationship between darkness language and severe depression—rather than metaphorical language broadly—supports our hypothesis that darkness metaphors may reflect the altered sensory experience associated with depression. Given that impaired light sensitivity is common in current depression, we propose that individuals experiencing severe depression naturally gravitate toward darkness metaphors because these metaphors capture their embodied experience of disrupted light processing. The convergence of linguistic and neurobiological evidence suggests darkness metaphors are more than poetic devices, they may also represent linguistic biomarkers of impaired light sensitivity in severe depression.