Overview

The close relationship between loneliness and health is well-documented. In 2022, people who said they had a physical and/or mental health diagnosis were over three times as likely to be chronically lonely than those who said they did not [1]. And there is substantial evidence that having a lack of social connections significantly increases the risk of premature mortality.

How loneliness affects health

The exact mechanisms by which loneliness can cause negative health outcomes are difficult to demonstrate. Three main pathways have been suggested. These are [2]:

• Behavioural – health-risk behaviours that are associated with loneliness, such as smoking and physical inactivity. 
• Psychological – loneliness is associated with lower self-esteem, and limited use of active coping methods
• Physiological – impacts to health-related physiology like immune function and blood pressure 

Loneliness and social isolation can impact our behaviour, adversely influencing daily activities and functions. For example, loneliness is associated with an increase in difficulties with activities of daily living [3], and a greater risk of being inactive and smoking [3; 4]. There is also evidence that social support can influence medication adherence [5]. 

So as well as impacting health through psychological and physiological processes, loneliness and social isolation may also affect health indirectly through their effects on health-related behaviours.

Physical health impacts

The effect of loneliness and isolation on mortality is comparable to the impact of well-known risk factors such as obesity, and has a similar influence as cigarette smoking [6]. Loneliness can increase the risk of early mortality by 26% [7]. 

• Loneliness is associated with acute stress responses [8], increased risk of high blood pressure [9] and reduced immunity against infections [10]
• Research suggests that loneliness and social isolation could be linked with systemic inflammation [11]
• Loneliness is associated with a 29% increase in risk of incident coronary heart disease, and 32% increase in risk of stroke [2]
• Loneliness is considered a risk factor for type 2 diabetes [12]. One longitudinal study found that loneliness was associated with a twofold risk of type 2 diabetes [13]
• Loneliness is associated with poorer sleep quality [14]
• Social isolation and loneliness are risk factors for the progression of frailty [15]
• Loneliness can impact the immune system and metabolic regulation [16]
• Lower social connectedness is associated with higher chronic pain [17]
• A study on Parkinson’s disease showed that people who felt lonely experienced a 55% greater symptom severity than those who weren’t [18]

Mental health impacts

Poor mental health can lead to loneliness (for example, due to withdrawal or reduced capacity for interaction). But loneliness can also negatively impact mental health. So the relationship can go in both directions. 

In particular, experiencing severe and long-term loneliness can have a ‘damaging impact on our mental health’ [19].

• Loneliness puts people at greater risk of poorer mental health, including depression [20].
• Research estimates that 60% of people experiencing chronic loneliness experience mental distress, compared to 15% of people who are not chronically lonely [21].
• Loneliness and low social interaction are predictive of suicide in older age [22].
• People who are lonely are also more likely to ‘perceive regular events as stressful’ [16].
• Loneliness and isolation are associated with poorer cognitive function [23], and increased risk of cognitive impairment [24], in older adults. Loneliness puts individuals at greater risk of cognitive decline and dementia [25].

Loneliness can contribute to a decline in mental health. This can be through things like: having more time alone to ruminate on worries and negative thoughts, losing confidence in the ability to socialise, feeling overwhelmed in social settings, and not talking about how you feel, which can lead to feeling even more overwhelmed [26].

The stigma associated with both loneliness and mental health conditions – such as them being dismissed or trivialised by others – can also further reinforce loneliness [26].

Use of health services

People who are lonely are also more likely to rely on the use of health and social care services. 

• Loneliness is associated with more general practice contacts, emergency treatments, and hospital admissions [27].
• Older people living alone are 50% more likely to access emergency care services, and 40% more likely to have more than 12 GP appointments over a year [28].
• Research shows an association between loneliness and higher mental healthcare expenditure [29].

The role of loneliness in influencing use of healthcare could be both direct, or indirect (for example, through its impact on health-related behaviours which in turn lead to use of health services).