The SSRI citalopram increases the sensitivity of the human circadian system to light in an acute dose.
E M McGlashanL S NandamP VidafarD R MansfieldS M W RajaratnamSean W CainPublished in: Psychopharmacology (2018)
Increased sensitivity of the circadian system to light could assist in explaining some of the inter-individual variability in antidepressant treatment responses, as it is likely to assist in recovery in some patients, while causing further disruption for others.