Night-time accidents are not only more frequent than daytime accidents. Theyare also more serious. One suggestion to mitigate this situation is toincrease lighting during the dark hours and create conditions more similar todaytime driving. This paper presents an investigation in which impact ofdifferent lighting conditions on drivers behaviour was studied. Tests werecarried out in real driving conditions on French and Belgian motorways onstretches where lighting were more frequent or continuous. Occurrences ofmicro-sleep and hypovigilance were analysed and compared with occurrences onstretches with more normal lighting conditions. It was found that morecontinuous lighting not necessarily improve vigilance. On the contrary, itmight even have adverse effects when it comes to driving longer distances. Inorder to improve traffic lighting it is proposed that drivers' behaviourshould be accounted for.