Depression, sleep disturbance, and vasomotor symptoms are common in breast cancer survivors (BCS), especially in younger women diagnosed before menopause. Risk factors and mechanisms for depression in this population are relatively unexplored. In 163 young BCS, vasomotor symptoms were significantly associated with higher depressive symptoms (β = 0.26, p = 0.001) and 64 % of the total effect was mediated through sleep disturbance (beta for specific indirect effect = 1.296, 95 % CI 0.591-2.212). Treatments reducing vasomotor symptoms might alleviate sleep disturbance and depression in this population.