The present study examined the association between workaholism, the tendency to work excessively hard in a compulsive fashion, and sleep problems among Japanese nurses. A cross-sectional survey was conducted among 600 nurses from 2 university hospitals in Japan using a self-reported questionnaire on workaholism, sleep, job-related variables (i.e., job demands, job control, and worksite support), and demographic variables. A total of 394 nurses returned the questionnaire (response rate=65.7%) and complete data from 312 female nurses were used for analyses (final coverage rate=52.0%). Workaholics, as measured using the Japanese version of the Dutch Workaholism Scale, were defined as those having high scores on both the “work excessively” and “work compulsively” subscales. Logistic regression analyses revealed that workaholics had higher risks for sleep problems in terms of subjective sleep insufficiency, excessive daytime sleepiness at work, difficulty awakening in the morning, and feeling tired when waking up in the morning (odds ratios [OR] of 4.40, 3.18, 3.48, and 4.61, respectively, p<0.05). These remained significant even after adjusting for demographic and job-related variables (OR 3.41, 5.36, 2.56, and 2.77, respectively). However, no significant associations were found between workaholism and insomnia symptoms. These results suggest that workaholic nurses had higher risks for impaired awakening, insufficient sleep, and workplace sleepiness.