Objectives: This study was conducted to: 1) describe sleep duration, fatigue, daytime sleepiness, and occupational errors among Thai nurses and 2) explore the influence of sleep duration on fatigue, daytime sleepiness, and occupational errors. Methods: A cross-sectional design was implemented. A convenience sample of 233 full-time nurses with at least one year of work experience was recruited to participate in the study. Data were collected using self-reported questionnaires and 1-week sleep diaries. Descriptive and logistic regression statistics were performed using SPSS software. Results: The mean total sleep time was 6.2 hours. Of the total participants, 75.9% (n=167) experienced short sleep duration, 38.2% (n=84) experienced fatigue, and 49.5% (n=109) experienced excessive daytime sleepiness. Occupational errors were reported by 11.7% (n=25). Medication errors, incorrectly performed procedures, and needle stick injuries were reported by 6.5% (n=13), 5.6% (n=12), and 4.7% (n=10), respectively, of participants performing the associated activities. The "Short Sleep Duration" group experienced more fatigue ( p =.044) and excessive daytime sleepiness ( p =.001) compared with the "Adequate Sleep Duration" group. Although occupational errors were more common in the "Short Sleep Duration" group, the difference between the two groups did not reach the level of statistical significance. Multivariable logistic regression analysis found that short sleep duration was a statistically significant risk factor for excessive daytime sleepiness (OR=2.47, 95% CI=1.18-5.19). Conclusions: The majority of registered nurses experience short sleep duration. Short sleep duration increased the risk of excessive daytime sleepiness but not fatigue or occupational errors. Adequate night-time sleep is paramount for preventing daytime sleepiness and achieving optimal work performance.