Night-time accidents are not only more frequent than daytime accidents. They are also more serious. One suggestion to mitigate this situation is to increase lighting during the dark hours and create conditions more similar to daytime driving. This paper presents an investigation in which impact of different lighting conditions on drivers behaviour was studied. Tests were carried out in real driving conditions on French and Belgian motorways on stretches where lighting were more frequent or continuous. Occurrences of micro-sleep and hypovigilance were analysed and compared with occurrences on stretches with more normal lighting conditions. It was found that more continuous lighting not necessarily improve vigilance. On the contrary, it might even have adverse effects when it comes to driving longer distances. In order to improve traffic lighting it is proposed that drivers' behaviour should be accounted for.