The aim of the paper to reflect on the meaning of the sense of loneliness caused by illness. The work is a selective narrative review with particular emphasis on attempts to define the feeling of loneliness, as well as the results of own research. The problem of loneliness affects not only patients, but also their families and caregivers. As it follows from the literature review, the issue of loneliness has been much better studied in mental disorders than in somatic diseases. In addition, the analysed research shows that the presence of the disease is the main variable determining the feeling of loneliness in the population of people in late adulthood. The feeling of loneliness turns out to be a key element of the psychosocial aspect of any disease. Therefore, it would be necessary to consider in the future how this adverse psychosocial phenomenon could be prevented.
Keywords: mental disorders; sense of loneliness; somatic diseases.