1. Psychology Program, School of Social Sciences, Nanyang Technological University, 48 Nanyang Avenue, Singapore 639818, Singapore
2. Sleep Education and Research Laboratory, UCL Institute of Education, London WC1H 0AA, UK
3. Affiliative Behaviour and Physiology Lab, Department of Psychology and Cognitive Science, University of Trento, 84 Corso Bettini, 38068 Rovereto, Italy
4. Department of Clinical Oncology, Imperial College Healthcare NHS Trust, Charing Cross Hospital, London W6 8RF, UK