Purpose <p>The aim of this study was to investigate whether having children and engaging in caregiving responsibilities influence the regularity of sleep–wake rhythms in men, particularly in terms of reducing the phenomenon of social jet lag—the misalignment between biological and social time.</p> Methods <p>This cross-sectional study was based on self-reported data collected online in the fall of 2023. Social jet lag was calculated as the difference between sleep timing on workdays and non-workdays. Statistical analyses included the Shapiro–Wilk test, Student’s <i>t</i>-test, Mann–Whitney <i>U</i> test, chi-square test, and binary logistic regression. Group comparisons between four categories (fathers and childless men, with and without social jet lag) were performed using the Kruskal–Wallis test. The study sample consisted of 238 adult men (mean age = 28 years; SD = 9.05). The questionnaire included questions about the number and age of children, relationship status, sleep habits, alcohol use, and sleep medication intake. Individuals with irregular circadian patterns or shift work were excluded.</p> Results <p>Social jet lag was significantly less prevalent among fathers compared to childless men. Having children was associated with a 70% lower likelihood of experiencing social jet lag. Fathers woke up earlier on both workdays and non-workdays and showed less variation in sleep timing between weekdays and weekends. No significant differences were observed in sleep duration on workdays or in overall average sleep time; however, fathers slept an average of 30&#xa0;min less on days off.</p> Conclusions <p>Fatherhood appears to promote a more regular sleep–wake schedule, which may reduce the incidence of social jet lag. While having children does not affect sleep duration during the workweek, it leads to less sleep extension on non-workdays. The child’s routine may act as an external <i>zeitgeber</i>, helping stabilize the father’s circadian rhythm.</p>