Postpartum emotional distress is very common, with 10%-20% of postpartum women reporting depressive or anxiety disorders. Sleep is a modifiable risk factor for emotional distress that has a pivotal role in postpartum adjustment. The present study aimed to examine whether sleep duration and quality during pregnancy predict trajectories of emotional distress in the postpartum period. Participants were 215 women that were assessed from the third trimester of pregnancy to 18-months postpartum. At all five time points (third trimester, 3-, 6-, 12-, and 18-months postpartum), measures of sleep duration and quality (measured by wake time after sleep onset; WASO) were derived from both actiography and diary-based measures. Repeated measures of depression and anxiety symptoms were collected using self-report measures. Results indicated four bivariate postpartum depression and anxiety growth trajectories, including (a) high comorbidity (5.4%); (b) moderate comorbidity (19.4%); (c) low anxiety and decreasing depression symptomology (18.6%); and (d) low symptomology (56.6%). Multinomial logistic regression analyses showed that mothers with shorter sleep durations during pregnancy were more likely to belong to the high comorbidity or moderate symptoms classes compared to the low symptomology class. In addition, mothers with higher WASO (i.e. lower sleep quality) at 3-months postpartum were more likely to belong to the moderate class compared to the low symptomology class. Given the potential negative implications of disrupted sleep in the perinatal period, the present study may inform future intervention studies that target sleep problems during pregnancy.© 2020 European Sleep Research Society.