Objective
To identify within-family groups according to sleep schedule, problems, and impact, reflecting similarities or differences in adolescents, mothers, and fathers and to examine how mental health and attachments associate with these triadic sleep groups.

Background
Family relationships shape sleeping, but within-family research in adolescence is scarce.

Method
Adolescents (17-18 years; 60% girls; n = 438), mothers (n = 448), and fathers (n = 358) filled in the Pittsburgh Sleep Quality Index. The adolescents reported mental health problems by the Behavior Assessment System and the parents by the General Health Questionnaire. All reported attachments by the Experiences in Close Relationships.

Results
Cluster analysis identified four triadic sleep groups: "Good family sleep" (47%), "Poor adolescent and maternal sleep" (29%), "Poor paternal sleep" (16%), and "Poor family sleep" (8%). Adolescents in the "Poor family sleep" group had more mental health problems than they did in other groups, and fathers in the "Poor paternal sleep" group showed higher psychiatric symptoms than in the "Good family sleep" or "Poor adolescent and maternal sleep" groups. Adolescents in the "Poor family sleep" group reported higher insecure-anxious attachments than they did in other groups, and fathers reported higher insecure-avoidant and insecure-anxious attachments in the "Poor paternal sleep" than they did in other groups.

Conclusion
A family systems approach provides new insight into sleep, mental health, and attachments.

Implications
Interventions to improve sleep quality should consider family dynamics that may underlie potential sleep problems, and sleep as a public health issue can benefit from knowledge about family mental health and attachments.