Bidirectional associations between accelerometer-based sleep metrics and mental health symptoms from childhood to late adolescence: data from a Brazilian birth cohort.

Background: A bidirectional relationship between sleep and emotional/behavioral problems has been suggested in the literature; however, no study has examined this association longitudinally across multiple developmental stages using objective sleep metrics. This study investigated the reciprocal relationship between sleep and emotional/behavioral symptoms and explored the potential existence of critical or sensitive periods within a Brazilian birth cohort.

Methods: The 2004 Pelotas Birth Cohort Study recruited 4231 children (2196 boys) born in 2004 in Pelotas, Brazil. Emotional/behavioral problems were evaluated using the Strengths and Difficulties Questionnaire (SDQ) at 6, 11, 15, and 18 years of age and analyzed as externalizing and internalizing symptoms. Sleep duration and efficiency were evaluated using actigraphs during the mentioned follow-ups. Cross-lagged panel models were used to assess bidirectionality and critical/sensitive periods.

Results: Higher externalizing symptoms at 6 years predicted longer sleep duration (β = 0.032, p = 0.041) and decreased sleep efficiency (β = - 0.034, p < 0.022) at age 18. The association was more evident in early adolescence, from 11 to 15 years β = 0.058, p = 0.005; β = - 0.059, p < 0.001). A bidirectional relationship was observed for internalizing symptoms and sleep duration from 11 to 18 years (β = - 0.039, p = 0.008; β = 0.061, p > 0.001), and higher internalizing scores at age 15 were significantly associated with reduced sleep efficiency at age 18 (β = - 0.034, p = 0.022).

Conclusions: Higher externalizing symptoms predicted poorer sleep efficiency and longer sleep duration, whereas a bidirectional association with an opposite relationship to internalizing symptoms was found. These results highlight that adolescence is a critical point for both associations.