SummaryAlthough prior research demonstrates the interdependence of sleep quality within couples (i.e., the sleep of one partner affects the sleep of the other), little is known about the degree to which couples’ sleep hygiene behaviours are concordant or discordant, and if one's own sleep hygiene or their report of their partners’ sleep hygiene is related to worse relational, psychological, and sleep outcomes. In a sample of 143 mixed‐gender, bed‐sharing couples, each partner completed an online questionnaire consisting of the Sleep Hygiene Index (for themselves and their partner), PROMIS sleep disturbance scale, conflict frequency, PHQ‐4 for anxiety and depressive symptoms, and the Perceived Stress Scale. Paired samples t‐tests between partners were conducted using total and individual‐item Sleep Hygiene Index scores to examine similarities and differences. Intraclass correlation coefficient (ICC) scores of dyadic reports were conducted to examine the level of agreement between each partner's sleep hygiene. Finally, we examined associations between one's own sleep hygiene and their report of their partner's sleep hygiene with both partner's sleep quality, emotional distress, and conflict frequency in a dyadic structural equation model with important covariates and alternative model tests. The results revealed a significant difference between men's (M = 14.45, SD = 7.41) and women's total score self‐report sleep hygiene ([M = 17.67, SD = 8.27]; t(142) = −5.06, p < 0.001) and partners only had similar sleep hygiene for 5 out of the 13 items. Examining dyadic reports of sleep hygiene revealed that partners had moderate agreement on their partners’ sleep hygiene (0.69–0.856). The results from the dyadic structural equation model revealed that poorer sleep hygiene was associated with one's own poor sleep quality, higher emotional distress, and more frequent relational conflict. For both men and women a poorer report of a partner's sleep hygiene was associated with one's own report of higher relationship conflict. Finally, men's poorer report of a partner's sleep hygiene was related better to their own sleep quality but was related to poorer sleep quality for their partners. These results have implications for sleep promotion and intervention efforts as well as for couple relationship functioning.