Social isolation and loneliness are both terms that denote a degree of social disconnection. Social isolation is an objective state marked by few or infrequent social contacts. Loneliness is the subjective and distressing feeling of social isolation, often defined as the discrepancy between actual and desired level of social connection.
Social connection and connectedness encompass a variety of terms used in the scientific literature (for example, social support, social integration, social cohesion) that document the ways that being physically or emotionally connected to others can influence health and well-being.
In this HA Brief, the author explains that loneliness impact on health may be greater than we think. Rather than being alarming, she shows a description of the situation, the evidence and a proposal for policy agenda.
And if you are not convinced, than I would suggest this book:
