Catastrophizing about sleeplessness has been investigated in adults and children, but little is known about adolescents. This article aimed to (a) investigate whether early adolescent girls catastrophized about consequences of sleeplessness, (b) describe topics in catastrophizing sequences, (c) examine the association between sleep quality and catastrophizing, and (d) assess whether puberty moderated this association. Girls (n = 115) between 11 and 12 years old completed adapted versions of the Pittsburgh Sleep Quality Index, the Pubertal Developmental Scale, and the Catastrophizing Interview. Twenty-four (21%) participants produced catastrophizing sequences, including concerns about school and mood. Sleep quality was associated with catastrophizing ( = 0.19, p = .042); however, puberty did not moderate this association ( = 0.15, p = .126). Findings highlight the importance of sleep-related cognitions in adolescent girls.