Background In a previous paper in Philos Ethics Humanit Med, the 1937 Swedish novel Sömnlös (Swedish for sleepless) by Vilhelm Moberg was used as background for a thought experiment, in which last century’s progresses concerning the safety of sleeping pills were projected into the future. This gave rise to a theoretical discussion about broad medico-philosophical questions such as (among other things) the concept of pharmaceuticalisation. Methods In this follow-up paper, the theme of insomnia in Sömnlös is complemented by a discussion (...) of the concept of nostalgia. The core of the paper is a theoretical discussion about the benefits and risks of nostalgia, bringing together some aspects of recent psychological research about the construct of nostalgia with the main story line of the novel. Results and Conclusion Nostalgia is portrayed as being, in some sense at least, ultimately beneficial for the protagonist of Sömnlös. This is congruent with recent psychological research. However, the story also shows that nostalgia may lead to problematic behaviours, at least when viewed from a virtue ethics perspective. Hence, nostalgia is both what leads the protagonist into ethically problematic behaviour and that which (paradoxically) ultimately saves him from his initial lack of courage, justice, temperance and practical wisdom. Moreover, the protagonist does not only “grow” ethically but also existentially. Hence, the novel opens up the possibility that insomnia and nostalgia might be viewed as bearers of important existential information (cf. sociologist of religion Peter L. Berger and his concept of “signals of transcendence”). (shrink)