Previous research has documented the importance of parenting on adolescent health and well-being; however, some of the underlying mechanisms that link the quality of parent-child relationship to health, adjustment, and well-being are not clearly understood. The current study seeks to address this gap by examining the extent to which sleep functioning mediates the effects by parental warmth on different measures of adolescent problem behaviors. Specifically, we test whether sleep functioning, operationalized by sleep quality and sleep quantity, mediates the relationship between the parental warmth and three measures of problem behaviors, namely alcohol use, illegal drug use, and deviance, in two nationally representative samples of Georgian (N = 6,992; M = 15.83, 60% females, and Swiss (N = 5,575; M = 17.17, 50% females) adolescents. Based on tests for parallel mediating effects by sleep functioning of parental warmth on problem behaviors in the MEDIATE macro in SPSS, the findings provided evidence that both sleep quality and sleep quantity independently and cumulatively mediated the effects of parental warmth on each of the three problem behaviors in both samples, with one exception. These results highlight the salience of positive parenting on sleep functioning among teens in two different cultural contexts, and, in turn, on measures of problem behaviors.