Earlier studies that have investigated the association between nomophobia and insomnia revealed that a strong relationship exists between both variables. This study aimed to explore possible associations between these variables and their impact on physical and mental health outcomes using a cross-sectional study design and mobile phone apps to collect data. Using a survey approach, data were collected from 444 participants (52% female, mean age 34 ± 12) using the Nomophobia Questionnaire (NMP-Q), the Insomnia Severity Index (ISI), the Morningness–Eveningness Questionnaire (MEQ) and three Android mobile phone apps. The Plees Tracker, screen time, and pedometer apps aided in collecting data on sleep duration, time spent on screen per day, and how close the phone was to the person. A statistically significant association was noted between nomophobia and insomnia, nomophobia and the eveningness chronotype, and nomophobia and screen time. The eveningness chronotype was also associated with an increased screen time use. The results show that NMP-Q, ISI, and screen time increase according to the chronotype. No statistically significant differences were noted in daily steps or sleep duration according to chronotype. The findings suggest that interventions targeting nomophobia may be beneficial in addressing insomnia among adults, particularly those with an evening chronotype. Future studies should consider exploring the causal relationship between them.