What Works Centre for Wellbeing, 2019
This review was undertaken in response to that fact that the evidence on loneliness is scattered and tends to be focused on single population groups, and most often considers older people only. It sought to address some of the challenges brought about by a lack of clarity in definitions of loneliness and related concepts, and how they should be evaluated, measured and applied in policy and practice.
The research looked at studies published worldwide since 1945 and found 144 qualitative sources conceptualising loneliness across the adult life course. In these studies, three types of loneliness were identified: social loneliness, emotional loneliness and existential loneliness