Singlehood affects people differently. For those who have been in abusive relationships, it can be a time of peaceful independence. For others, it can feel like a curse that results in daily feelings of hopelessness and despair.

One of the key differences between singlehood groups is the degree of loneliness. Often perceived as unmet social needs or inadequate meaningful connections, loneliness is more than just a fleeting emotion. It can have a profound impact on physical health, with implications that go beyond mere emotional distress.

Loneliness might also account for why singlehood status has long been associated with a host of negative life outcomes, such as decreased mental health and higher mortality rates. But what are the mechanisms at play here? A recent scientific review in Biodemography and Social Biology outlines the ways loneliness might get “under the skin” and affect the mind and body in negative ways. Here, I discuss the six key things that really jumped out at me in the article.

 

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Loneliness in the body

Loneliness doesn't just affect our emotions; it takes a toll on our bodies. Its influence extends to physiological pathways, including the hypothalamic-pituitary-adrenal (HPA) axis, inflammation, metabolism, repair, and brain functioning. Chronic loneliness may trigger hypervigilant stress responses, dysregulating our HPA axis and causing adverse health conditions. The cumulative impact of physiological alterations is proposed to constitute an "immunometabolic syndrome," highlighting the interconnectedness of loneliness and health. Essentially, loneliness can put us in an enduring stressful state, mobilising the body's resources to protect us from harm.

Epigenetic Changes

There is some evidence that loneliness might affect the body by changing how our genes work. Methylation, the attaching of methyl groups to gene promoters, is part of the Conserved Transcriptional Response to Adversity (CTRA). This CTRA response causes genes in the body to become more or less active when an individual faces difficult social situations. While more research is needed, these gene expression patterns linked to negative health outcomes.

Telomeres and Aging

Telomeres, repetitive DNA sequences at the ends of chromosomes, are suggested to be influenced by psychological factors like loneliness. Telomeres get shorter as cells duplicate, meaning that we can actually infer someone’s age from their telomere length. Interestingly, we can also establish whether individuals are aging faster than we might expect given their chronological age. Some research finds that individuals who are chronically lonely have shorter telomeres—loneliness might literally cause people to age more rapidly.

Though a potentially mind-blowing finding, there are some inconsistencies in the literature, which points to the need for further research to understand the potential role of loneliness in biological aging.

Substance Misuse

Loneliness is connected to various substance use problems, creating a complex bidirectional relationship. It is said that people abuse substances to either feel something, or to stop feeling something. And those who regulate their emotions by smoking, alcohol use, cannabis, and opiates may be doing just that. The bidirectional relationships suggest that substance misuse itself might cause more loneliness in turn—by harming the relationships we already have, for example.

The intricate dance between loneliness and substance use suggests plausible accounts in both directions, making it a multifaceted aspect of the loneliness-health connection.

Health-Related Behaviours

More than just a feeling; loneliness influences our health-promoting actions. It's linked to lower levels of physical activity, malnutrition risk, unintended weight loss, eating behaviours, and medication non-adherence in older adults—a lot of the same symptomology as depression.

Essentially, lonely people find it harder to motivate themselves to look after their health. This became very clear during the recent COVID-19 pandemic, with loneliness seemingly reducing health-promoting behaviours such as distancing and mask-wearing.

Sleep Disturbance

A lack of connectedness with others can also disrupt our sleep. Meta-analyses reveal moderate associations between loneliness and sleep problems across various age groups. Loneliness consistently correlates with sleep disturbance, both self-reported and objectively measured, reinforcing the robust link between loneliness and sleep problems.

Further Thoughts

While it can be tempting to dismiss someone's feelings of loneliness, they should not be taken lightly. As we navigate the silent epidemic of loneliness, it's clear that it's not just an emotional state. Loneliness weaves a complex web that influences physiological processes, epigenetic changes, health-related behaviours, and even genetic factors.

For a long time, the mechanisms by which loneliness leads to negative outcomes were unknown. And to some extent, they still are. We have established only a few links in the chain of events that take people from that intense, unconnected feeling through to poorer health outcomes. With time, comprehensive research, advanced study designs, and effective interventions will help us to unravel the intricacies of loneliness and its impact on physical health.

In the meantime, it is worth recognising how impactful loneliness can be. This research can also give some food for thought for those who are single. Lonely singles, especially men, in my experience, tend to dismiss the idea of trying to reduce their feelings of loneliness by enhancing the other, non-romantic relationships in their lives. This can be seen as a “consolation prize” or a dismissive quick fix.

However, with what we know about how loneliness affects the body, developing such relationships could be a way of partially mitigating the physical and psychological effects of unwanted singlehood and maybe even make us a more well-rounded and attractive person in the process.