Abstract
STUDY OBJECTIVES: Children with evening chronotype may be at risk for insufficient sleep because their chronotype makes it difficult to sustain healthy sleep habits. We evaluated bidirectional relationships between chronotype and sleep hygiene. METHODS: Two hundred forty-six children (n = 246 at T1, n = 200 at T2, n = 147 at T3), with a mean age of 9.9 (SD=1.4) at T1, participated in a longitudinal study on sleep and substance use. Participants either had a parental history of alcohol use disorder or were matched controls. The Adolescent Sleep Hygiene Scale measured sleep hygiene. Chronotype was measured using the Morningness/Eveningness Questionnaire. We used random intercept cross-lagged panel models to examine longitudinal relations between chronotype and sleep hygiene across three time points, each approximately 1 year apart. RESULTS: Chronotype at T1 predicted sleep hygiene at T2 (b=0.38, p < .05). Chronotype at T2 predicted sleep hygiene at T3 (b=0.38, p < .05). T1 Sleep Hygiene predicted chronotype at T2 (b=0.27, p < .05). T2 Sleep Hygiene predicted chronotype at T3 (b=0.24, p < .05). Chronotype also predicted itself over time (T1-T2: b=0.31, p < .05; T2-T3: b=0.31, p < .05). Sleep hygiene did not predict itself at future time points. Parental history of alcohol use disorder did not predict sleep hygiene or chronotype. CONCLUSIONS: There is a bidirectional relationship between chronotype and sleep hygiene; more eveningness predicts poorer sleep hygiene at a later time point, and poorer sleep hygiene predicts more eveningness later. Sleep hygiene is not stable over time and may be a more modifiable target for public health interventions than chronotype.