Organisms and their cells exhibit alternating phases of activity and inactivity that are regulated by internal ~24h (circadian) clocks. These clocks synchronize to natural changes in day-light, but likely also to other factors including the activity of the social group. Although the molecular mechanisms behind such clocks have been extensively investigated, we understand little about circadian rhythmicity in a social context. Here, we investigate how individual shorebirds cope with misalignment between their circadian clock and social time (“social jet lag”) – a phenomenon studied in only few species (mainly humans and other mammals). The SocialJetLag project has three main objectives and implications. First, SocialJetLag is testing the applicability of a new method for general research in birds. The method quantifies rhythms in circadian clock genes and hence will allow minimally invasive bio-rhythm sampling in the future. Second, SocialJetLag is quantifying internal rhythms in a vertebrate that lives in an inter-tidal zone and under the 24h day-night for 10 month of the year and breeds under the continuous day-light of the Arctic. Internal rhythms of organisms facing such complex environmental cues are so far unknown, but key to generalize current findings from invertebrates. Finally, SocialJetLag is investigating how individuals cope with social jet lag and synchronize to the timing of their group – an important topic in the field of ‘time research’.