<p>Chronotype, an individual’s preference of their sleep and wake cycle, has been associated with smartphone addiction, which may lead to bedtime procrastination. However, little has been reported on their symptom-level interconnections as well as the effect of smartphone addition intervention on bedtime procrastination. The present research consisted of 2 studies. Using Bayesian network analysis in a sample of 990 neurotypical individuals, Study 1 assessed the relationships between subdimensions of smartphone addiction, bedtime procrastination and chronotype, in which the Smartphone Addiction Scale (SAS), Bedtime Procrastination Scale (BPS) and the Morningness-Eveningness Questionnaire (MEQ) were administered. Study 2 was a pilot intervention that applied the Nudge-Based Intervention to ameliorate smartphone addiction and therefore bedtime procrastination among young adults (<i>n</i> = 26), while assessing their chronotypes. Outcomes of both the Intervention and Control groups were measured after a training / wait list time for 2 weeks. In Study 1, within the undirected network, cyberspace-oriented relationship emerged as the most central node. The strongest bridge nodes, based on bridge strength, were identified as nodes representing chronotype and bedtime procrastination. Overuse of smartphone played an activating role, impacting other nodes. In the Bayesian network, BPS acted as a mediator, exhibiting reciprocal influences on both subdimensions of smartphone addiction and the MEQ, with the MEQ taking on a recipient role. In Study 2, the mean scores of SAS and BPQ in the Intervention group decreased significantly from baseline to post-intervention. The intervention group were also more transformed into morningness and had less average screen time. In general, the 2 studies illustrated an intricate network linking symptoms of smartphone addiction to both chronotype and bedtime procrastination. Importance of cyberspace-oriented relationships as a central symptom was implied. Furthermore, preliminary test of Nudge-Based Intervention in order to curb smartphone addiction yielded promising results. Future attempts to reduce bedtime procrastination by targeting smartphone addiction may have profound potentiality.</p>