Acknowledgements
sleep stage
The authors are grateful to Irmeli Dahlblom and Leena Vierikko (Turku PET Centre, University of Turku, and the Hospital District of Southwest Finland) and Milla Karvonen (Department of Psychology and Speech-Language Pathology, University of Turku) for assistance during the experimental sessions. The authors also thank the staff in Turku PET Centre, especially radiographers Minna Aatsinki, Anne-Mari Jokinen, and Hannele Lehtinen, and medical laboratory technologists Sanna Suominen and Heidi Partanen for assistance during the imaging sessions. The authors further wish to express their gratitude to sleep technician Kati Lahtinen (Sleep Research Centre at the University of Turku) for offline sleep stage scoring, and Maria Ek and Teemu Laine (Department of Psychology and Speech-Language Pathology, University of Turku) for the background support. Finally, the authors thank all participants for contributing to the experiments.