Dr. Maarten C. Eisma is Associate Professor of Clinical Psychology at the University of Groningen, the Netherlands. His research focuses on the causes, consequences, and treatment of severe and persistent grief (i.e. prolonged grief). He has helped develop multiple internet-based interventions for prolonged grief and Dutch practice guidelines for grief in palliative care. He has published over 90 peer-reviewed papers and book chapters. In April 2023, he received the ADEC Research Recognition Award. Thomas A. de Lang is a PhD-student who has investigated the bi-directional effects of sleep on grief and risks for the development of chronic insomnia. He will be leading a therapeutic intervention study examining the effects of evidence-based insomnia therapy on sleep and prolonged grief. Prof. Dr. Marike Lancel is professor of Clinical Psychology at the University of Groningen, expert in sleep medicine and head of research of the Center of Expertise on Sleep and Psychiatry, Mental Health Service, Assen, the Netherlands. Her main research theme is the reciprocal relation between sleep disturbances and symptom severity of affective and stress-related disorders. She is co-founder of the Center of Expertise on Sleep and Psychiatry and co-editor of the Dutch book Sleep Disorders in Psychiatry: Diagnosis and Treatment.