Poor sleep quality and inadequate sleep in adolescents are a rising
trend globally. The Theory of Planned Behaviour (TPB)—which centres
on an individual’s attitude toward performing the behaviour, subjective
norms and perceived behavioural control—has been applied to examine
sleep hygiene behaviours in young adults. We expanded on prior works
by using a longitudinal design to examine the effects of TPB factors,
together with sleep hygiene knowledge and planning constructs, on
sleep hygiene behaviours and on sleep quality and health in a group of
Iranian adolescents. A total of 1822 healthy adolescents (mean
age = 13.97) from 25 high schools in Qazvin, Iran, completed a selfreported
survey at baseline and 6 months later. Structural equation modelling
(SEM) was used to delineate the pathway from adolescents’ sleep
hygiene knowledge, TPB constructs of their behavioural intentions and
sleep hygiene behaviours and their sleep quality and self-reported
health. The SEM model demonstrated that although behavioural
intention, coping planning and action planning predicted the sleep
hygiene behaviours positively 6 months later with acceptable model fit
[comparative fit index (CFI) = 0.936; Tucker–Lewis index (TLI) = 0.902;
root mean square error of approximation (RMSEA) = 0.080; standardized
root mean square residual (SRMR) = 0.044], sleep hygiene
knowledge did not predict behavioural intentions significantly. Sleep
hygiene behaviours were associated with sleep quality and psychiatric
wellbeing. Thus, the TPB, combined with coping and action planning, is
useful in understanding the sleep hygiene behaviours of adolescents.
Health-care providers may want to emphasize TPB constructs and
coping and action planning to improve adolescents’ sleep hygiene
behaviours, rather than rely solely upon increasing adolescents’ sleep
hygiene knowledge