Since its introduction, there have been differing views and conflicting positions on the merits of so-called ‘summer time’, and calls for a change to the summer time arrangements have been made repeatedly from various quarters. Against this backdrop, the TAB working report ‘Assessment of Summer Time’ reviewed the scientific findings and experience regarding summer time available to date and presented them in a comprehensive overview. The report concludes that the body of scientific studies and findings on the possible effects of summer time is very limited and patchy. Nevertheless, it provides no evidence that the annual time changes result in any significant positive or negative effects on energy consumption, the economy or health. In this respect, the question of whether the ‘clock change’ should be retained or abolished will remain, for the foreseeable future, the subject of political and social debates that can draw only to a limited extent on scientific facts. Whatever the outcome of these debates, however, any change to the current provisions can only be made by revising the relevant EU directive through a proper legislative procedure at Union level. A unilateral, national withdrawal from the scheme is not possible.