LHB and mood disorder: Given the overlapping influence of the LHb and DRN on circadian rhythmicity and mood disorders, we assessed whether exposure to chronic social defeat stress (CSDS) affects: (i) diurnal rhythmic activity of LHb cells projecting to the DRN (cellsLHb→DRN); (ii) DRN cells; and (iii) the ability of mice to reentrain to a new photoperiod.