Background: Recent research has found evidence of an association between motor vehicle accidents (MVAs) or near miss accidents (NMAs), and excessive daytime sleepiness (EDS) or its main medical cause, Obstructive Sleep Apnea (OSA). However, EDS can also be due to non-medical factors, such as sleep debt (SD), which is common among professional truck drivers. On the opposite side, rest breaks and naps are known to protect against accidents. Study objectives: To investigate the association of OSA, SD, EDS, rest breaks and naps, with the occurrence of MVAs and NMAs in a large sample of truck drivers. Methods: 949 male truck drivers took part in a cross-sectional medical examination and were asked to complete a questionnaire about sleep and waking habits, risk factors for OSA and EDS. Results: MVAs and NMAs were reported by 34.8% and 9.2% of participants, respectively. MVAs were significantly predicted by OSA (OR= 2.32 CI95%=1.68-3.20), SD (OR=1.45 CI95%=1.29-1.63), EDS (OR=1.73 CI95%=1.15-2.61) and prevented by naps (OR=0.59 CI95%=0.44-0.79) or rest breaks (OR=0.63 CI95%=0.45-0.89). NMAs were significantly predicted by OSA (OR= 2.39 CI95%=1.47- 3.87) and SD (OR=1.49 CI95%=1.27- 1.76) and prevented by naps (OR=0.52 CI95%=0.32- 0.85) or rest breaks (OR=0.49 CI95%=0.29- 0.82). Conclusions: When OSA, SD or EDS are present, the risk of MVAs or NMAs in truck drivers is severely increased. Taking a rest break or a nap appear to be protective against accidents.