Objective: Evidence suggests that caffeine use disproportionately impacts sleep functioning among youth with attention-deficit/hyperactivity disorder (ADHD). The present study aimed to examine the association of caffeine use with disrupted sleep, and to test moderating effects of ADHD, by leveraging differences within twin pairs to explore potential quasi-causal (i.e., within-pair) effects.
Method: N = 765 complete same-sex twin pairs (mean age at baseline = 10.14 [SD = .5]; 49% girls; 73% white) from the ABCD study reported caffeine use and frequency of disrupted sleep; parents reported youth ADHD symptoms. Cotwin control analyses predicted disrupted sleep from caffeine use, ADHD, and their interaction at ages 10 and 12.
Results: Neither quasi-causal within-pair effects of caffeine use on disrupted sleep, nor a moderating role of ADHD were identified. Posthoc biometric models indicated that genetic and environmental influences on these phenotypes may change over time, such that genetic influences on disrupted sleep began to emerge more robustly around early adolescence. Additionally, caffeine use and disrupted sleep, but not ADHD, displayed overlapping genetic influences (12-13% of total phenotypic variance) at age 10.
Conclusions: In a sample of preadolescent twin pairs from the ABCD Study, we did not observe evidence that caffeine use was quasi-causally associated with disrupted sleep at this early developmental stage. However, caffeine use and disrupted sleep emerged with shared etiologic influences. In sum, this study sets the stage for examining these dynamic patterns in future examinations of this critical and timely ABCD study sample, as genetic and environmental influences on behavior are known to change throughout development. (PsycInfo Database Record (c) 2023 APA, all rights reserved).