https://orcid.org/0000-0002-1710-5728
ABSTRACT
Loneliness is a construct that has increasingly been studied over the last decades. Although many people experience loneliness at some point in their lives without severe consequences, a vast body of empirical work has shown the detrimental effects of loneliness, suggesting that loneliness affects psychological well-being (e.g., depression, anxiety, lower self-esteem) as well as physical health (e.g., cardiovascular disease), and even early mortality. Recent theoretical work has suggested that the duration of loneliness might explain why loneliness might be beneficial for some people but destructive for others. Specifically, short-term loneliness might result in increased attempts to regain social connection and therefore serve an adaptive function, whereas long-term loneliness might result in maladaptive health outcomes. With this review, we highlight the double-edged sword of loneliness – that is, its adaptive function versus its maladaptive consequences – and we summarize the different ways in which previous work attempted to explain this phenomenon. Moreover, we aim to pinpoint some inconsistencies in the conceptualization and measurement of the duration of loneliness in previous work, and we offer considerations for future research to move the field forward.
The need to belong is a fundamental human need: We need to feel that we belong and that we are connected with others (Baumeister & Leary, Citation1995). When we miss something in our social relationships, either regarding the quantity or quality, this need to belong is frustrated and we experience an unpleasant, painful feeling – loneliness (Perlman & Peplau, Citation1981). Loneliness is, therefore, considered as an innate, biological warning system, serving an important adaptive function (Cacioppo et al., Citation2006; Qualter et al., Citation2015). More specifically, loneliness signals to people that something is wrong concerning their social relationships. Additionally, precisely because loneliness is such a painful experience, it also motivates people to invest the time and energy that is needed to maintain or repair their social relationships. When people (re-)establish their social relationships, the painful feeling of loneliness will disappear again.
Aside from this notion of loneliness serving an adaptive signalling and motivational function, is a vast field of research pointing towards the detrimental impact of loneliness on people’s current and future mental and physical well-being. Across the lifespan, people who experience loneliness, for example, also experience more depressive and anxiety symptoms, have lower self-esteem, report more suicidal behaviours, sleep problems, and cardiovascular incidents, go to the doctor more often, and have a substantially higher risk for early mortality (for reviews, see Hawkley & Capitanio, Citation2015; Holt-Lunstad et al., Citation2015; Leigh-Hunt et al., Citation2017; Maes et al., Citation2019).
The prevailing assumption in the literature to reconcile these seemingly contrasting sides of loneliness – its adaptive function versus its maladaptive consequences – concerns the duration of the experience (Vanhalst et al., Citation2015). When loneliness is a transient and temporary experience, it mainly serves an adaptive function, without further long-lasting negative consequences. However, when loneliness endures, it becomes problematic, having a far-reaching, negative impact on one’s mental and physical health. In this review, we discuss theoretical notions and empirical findings to further clarify this double-edged sword of loneliness. We first critically reflect on two broader perspectives in the literature: One assuming that the adaptive side of loneliness is a different type of experience than the maladaptive side of loneliness, and the other assuming more of a continuum where the adaptive side of loneliness gradually develops into something maladaptive. In both perspectives, the aspect of duration is a key explanation, although empirical work examining this explanation is limited. Next, we review some alternative explanations, that have received less attention in the literature so far, to reconcile the adaptive and maladaptive sides of loneliness.
The adaptive and maladaptive sides of loneliness: two different experiences
When loneliness leads to reconnection, can it be considered a similar experience than when loneliness is not leading to anything adaptive, except to more loneliness and even far-reaching maladaptive outcomes? Perhaps not. Although ‘duration’ is a continuous aspect of loneliness, it is usually not presented as such. Research aiming to take into account the duration of loneliness, most often separates ‘temporary’ from ‘chronic loneliness’ – presenting these as two separate categories. This approach is in line with the galloping horse fallacy, which challenges the idea that longer-term effects are identical to short-term processes, based on the analogy of a trotting versus galloping horse (Frijns et al., Citation2020). A trotting horse moves slowly, and these movements are qualitatively different from the movements of a galloping horse. ‘Speeding up a video recording of a trotting horse will not yield a galloping horse, nor vice versa’ (Frijns et al., Citation2020, p. 52). Although this research of Frijns et al. focused on adolescent secrecy in their relationship with parents, the galloping horse fallacy has been presented before in broader work on the developmental psychology of adolescents (Keijsers et al., Citation2018), and may be valid in the context of loneliness too. Specifically, in line with this metaphor, one could conclude that brief, temporary experiences of loneliness, leading to adaptive, short-term processes, are different experiences than the loneliness that endures for months or even years, detrimentally affecting one’s well-being.
This also implies that researchers and practitioners need to carefully consider what exactly they intend to measure – and what kind of timeframe would capture that best. To grasp the adaptive function of loneliness, the focus should be on rather short-term processes. Such processes can, for instance, be captured using experience sampling methodologies. For example, in a study of Reissmann et al. (Citation2021), a convenience sample of university students was followed for 14 days, including up to seven assessments per day. The authors found some evidence for the adaptive function of loneliness, as the results showed that after zero social contact, feeling lonely was related to increases in subsequent social contact levels. Indeed, these findings suggest that those feelings of loneliness might have worked as a motivational force.
Another way of focusing on short-term processes and examining the adaptive function of loneliness, could be by conducting experimental studies. Given that it is difficult, if not impossible, to induce feelings of loneliness in an ecologically valid way, most such studies focus on inducing social exclusion rather than loneliness. As social beings, social exclusion is generally a painful feeling, and is strongly related to feeling lonely (Allen et al., Citation2020; Heu, Citation2023; Williams, Citation2007). In a study by Maner et al. (Citation2007), for example, support was found in several experiments among university students for the social connection hypothesis, which states that the experience of social exclusion increases the motivation to form social bonds. More specifically, they found that the threat of social exclusion increased the interest in making new friends, the desire to work together with others, and the positive impression of new social targets.
Despite these examples, the adaptive and motivational function of loneliness is understudied and only few studies show empirical evidence for this hypothesis (Spithoven et al., Citation2017). Most studies, even when examining short-term processes, focus on negative correlates. As mentioned before, a large body of empirical evidence exists on the associations between loneliness and poor mental and physical health (for reviews, see Hawkley & Capitanio, Citation2015; Holt-Lunstad et al., Citation2015; Leigh-Hunt et al., Citation2017; Maes et al., Citation2019). Nevertheless, some studies focus on both short- and long-term processes, revealing important insights concerning the conceptual question whether adaptive and maladaptive sides of loneliness are two different types of experiences. For example, in a study among Chinese children (Zilioli et al., Citation2017), daily loneliness was strongly related to negative affect (reflecting the unpleasantness of the experience, which is assumed to motivate people to reconnect again), but only moderately with depression (reflecting that daily experiences of loneliness do not necessarily result in long-lasting negative consequences). Trait loneliness (i.e., loneliness of longer duration), on the other hand, was strongly related to depression. Another study, among German adults, however, found that trait and daily loneliness were rather similarly related to depression (Buecker et al., Citation2023).
Future work is urgently needed to further clarify this issue, and experience sampling methodologies might be a very promising avenue for such work. The focus on short-term processes of such study designs matches well with the underlying theoretical notion of the adaptive side of loneliness. Yet, an important limitation to keep in mind is that such studies generally do not examine how long the loneliness experiences have already lasted. Even individuals who are struggling with loneliness already for months or years, still experience fluctuations in their levels of loneliness across the day or from day to day. Moreover, if we assume that temporary loneliness (serving an adaptive function) is a different type of experience than long-term or chronic loneliness (having maladaptive consequences), this implies that there is a particular cut-off point. Most researchers would agree that experiencing loneliness for a week most likely reflects a normative and adaptive experience, while experiencing loneliness for years does not. But what about someone experiencing loneliness for 10 months? There currently is no consensus on the definition or operationalization of chronic loneliness. How long should someone’s loneliness last to be considered as chronic? And if a lonely person sometimes has periods without experiencing loneliness, how long can those periods be? Together, measuring and separating the short-term and long-term experiences of loneliness, for example by using an experience sampling methodology, and linking them to adaptive and maladaptive correlates, is an interesting and necessary avenue for future work. Important for such longitudinal research is to match the study design with theory about the processes at stake, considering ‘the time scale at which the process unfolds, the frequency with which important changes in the process occur, the overall duration of the process, and the timing of important events in the process’ (Hopwood et al., Citation2022, p. 884).
Still, before taking initiatives to reach such a consensus, it is imperative to reflect on the underlying conceptual assumptions. Is feeling lonely for 1 year really something qualitatively different from feeling lonely for 8 months? How meaningful would it be to develop such a cut-off point and how likely is it that the same cut-off point can be used for everyone? And, if we would link this to the treatments that we would offer – Would this mean that certain treatments will be available only for people who felt lonely for a particular period of time, even when they really suffer from the experience and ask for help?
The adaptive and maladaptive sides of loneliness: a developmental process
Most studies discuss the duration of loneliness as if one could distinguish between different forms of loneliness, comparing individuals who feel ‘temporary lonely’ with individuals who feel ‘chronically lonely’. Yet, the underlying theoretical rationale in the large majority of such studies reflect a rather gradual change in loneliness. It is assumed that instead of leading to reconnection, loneliness for some people endures and they get increasingly stuck in a vicious cycle where loneliness gets connected with pervasive long-lasting consequences (e.g., Hawkley & Capitanio, Citation2015; Lim et al., Citation2020; Qualter et al., Citation2015). Thus, this line of work does not consider both types of loneliness as two different experiences, but rather stresses that the consequences of loneliness change across time.
An influential model in the loneliness literature, the reaffiliation motive (RAM; Qualter et al., Citation2015), reflects this developmental process of people increasingly getting stuck in a vicious cycle. This model hypothesizes that loneliness activates the reaffiliation motive, leading to behavioural and cognitive processes that help people to regulate their behaviour to reconnect again. The cognitive processes include a hypervigilance for social cues to monitor social situations and possible social threats. According to the model, this hypervigilance is adaptive for reconnection, but in some people develops into an overattentiveness of social cues and negative interpretations of social information. These cognitive biases do not lead to reconnection but rather to behaviours that confirm the perceptions and feelings of disconnection. In other words, these individuals gradually get stuck in a self-reinforcing loop, leading to prolonged feelings of loneliness. However, as the authors also stated ‘there is no empirical work documenting whether and when an adaptive heightened orientation to social cues turns maladaptive’ (p. 260).
Although the RAM model is used as a theoretical framework in most studies that aim to take into account the duration of loneliness, only few of these studies actually operationalize the duration in a continuous way. Two examples of studies that measured the duration of loneliness as a continuous aspect are the studies of Qualter et al. (Citation2021) and Hojat (Citation1983). Qualter et al., asked participants to indicate for four indirect questions on loneliness (e.g., ‘do you feel left out?’) how long that feeling lasts when it occurs, ranging from ‘hours’ to ‘months’, or ‘longer’. In the study of Hojat, participants were also asked to reflect back on their loneliness experience, by asking how long their feelings of loneliness endured. Participants could, for example, indicate that they ‘never’ experienced loneliness, or ‘during the last four months’ up until ‘more than several years’ and ‘always’. However, based on their answer, participants were still grouped into categories, including ‘transitory loneliness’ (at least ‘some of the time’) and ‘chronic loneliness’ (‘more than a year’) – which seems to match better with the approach of viewing temporary and chronic loneliness as two different experiences. Still, in line with the overall idea that a shorter duration of loneliness is related to fewer negative consequences than a longer duration, it was found that individuals experiencing chronic loneliness reported lower self-esteem and higher anxiety as well as depression, compared to individuals experiencing temporary loneliness.
To summarize, the duration of loneliness has been put forward as an important explanation for the seemingly contradictory sides of loneliness, although more empirical work is needed to examine this hypothesis in depth. Moreover, this hypothesis is only one way to interpret the notion that loneliness has an adaptive function but clearly maladaptive consequences. Alternative explanations are possible, which we discuss in the next section.
Alternative ways to explain loneliness as a double-edged sword
In a recent study, Qualter et al. (Citation2021) extended the focus on the duration of loneliness as an explaining factor by including also measures of the frequency and intensity of loneliness. In their study, Qualter et al. mention that most loneliness measures ask about the frequency of the experience. For example, participants are asked how often they feel lonely, which they can answer on Likert-type scales ranging from ‘never’ to ‘often’ (or ‘always’). Notably, these measures are generally also used in studies that explicitly aim to focus on the duration of loneliness. For example, in studies with a longitudinal design, the same question (or questions, if an indirect measure of loneliness is used) is asked at multiple time points, after which subgroups of participants are constructed, usually including at least a ‘not lonely’, ‘temporary lonely’, and ‘chronically lonely’ group. This way, the ‘chronically lonely’ group typically consists of people that have repeatedly indicated that they ‘often/always’ feel lonely, leading to a mix of the duration and frequency aspect of loneliness.
The approaches that scholars have used to classify participants in these different groups are very diverse, making comparisons across studies rather challenging (for some examples, see Cohen-Mansfield et al., Citation2009; Jylhä, Citation2004; Patterson & Veenstra, Citation2010; Pengpid & Peltzer, Citation2023). Depending on the study design, participants need to report loneliness at two or more measurement waves to be considered as ‘chronically lonely’, and depending on the time-interval between waves, an individual categorized as experiencing ‘chronic loneliness’ might be someone feeling lonely for 1.5 year (e.g., Vanhalst, Rassart, et al., Citation2013) to more than five years (e.g., Ladd & Ettekal, Citation2013) or even longer. These studies found some evidence for the prevailing assumption in the literature that loneliness brings along maladaptive consequences especially when it endures over time. For example, adolescents experiencing chronic loneliness, compared to adolescents experiencing temporary loneliness, reported lower self-worth (Qualter et al., Citation2013) and higher levels of negative emotions and more maladaptive emotion regulation strategies (Vanhalst et al., Citation2015, Citation2018). However, when comparing different groups of people experiencing temporary loneliness (e.g., people who increase versus decrease over time in loneliness), results are less consistent and ‘temporary’ and ‘chronic’ lonely groups sometimes show similar outcomes (e.g., Qualter et al., Citation2013; Schinka et al., Citation2013; Vanhalst et al., Citation2012).
Besides these aspects of the duration and frequency of the loneliness experience, Qualter et al. (Citation2021) also highlighted the intensity of the experience as a relevant aspect to consider. It could for example be that after a particular event, someone feels lonely in a very intense and overwhelming way, but perhaps not for an extended period of time. Relatedly, people can experience loneliness for an extended period of time, but to different degrees of intensity and frequency (e.g., almost every day or only now and then). We suggest future research to disentangle the duration, frequency, and intensity of loneliness, and examine how they are – separate and in interaction – related to health outcomes. Would prolonged feelings of loneliness of lower frequency or intensity be less bad for one’s well-being than prolonged loneliness at a higher frequency or intensity? Interestingly, previous work (Qualter et al., Citation2021) indicated that the pattern of correlations among these three aspects of loneliness differed across different age groups (ranging from 16 to 75+), suggesting that different (combinations of) aspects might be relevant at different ages across the lifespan. We suggest future research to build on this work to further clarify this issue.
In addition to the aspects of duration, frequency, and intensity of loneliness, there might be other explanations for why loneliness sometimes merely serves an adaptive function but brings along many maladaptive consequences at other times. For example, the adaptive function of loneliness is usually linked to concrete events, such as starting at a new school, moving houses, or a relationship break-up. Perhaps the loneliness experience becomes less adaptive when this link is less strong or not there anymore, and especially when there never was a concrete event after which loneliness occurred for the first time. For example, feeling lonely after moving to a new school might help an adolescent to invest in social relationships in the new school during the first weeks, but might not be helpful anymore if the adolescent continues to feel lonely across the school year or if the adolescent also feels lonely in situations that are not related to the school-context. In a study by Rokach and Brock (Citation1995), participants were asked whether they experience loneliness ‘on a more-or-less continuous basis’ or ‘only when something happened’. This study found that people indicating to experience loneliness ‘on a more-or-less continuous basis’ more often indicated personal inadequacies, unfulfilling intimate relationships, and social marginality as causes of their loneliness experience than people indicating to experience loneliness ‘only when something happened’. More research is needed to further explore this potential explaining factor, with a focus on health outcomes.
Another factor that may help shed light on when and for whom loneliness is mostly adaptive without long-lasting consequences, is the amount of distress or impairment that is caused by loneliness. Even if you experience the painful feeling of loneliness, it might not or only mildly impair your daily life (especially when the adaptive function of loneliness still prevails over its maladaptive consequences). A starting point to develop such items to assess the experienced impairment of loneliness, could be the Overall Anxiety Severity and Impairment Scale (OASIS; Norman et al., Citation2006) and the Overall Depression Severity and Impairment Scale (ODSIS), which was developed based on the OASIS (Bentley et al., Citation2014). Both scales consist of five items, with the first two items referring to, respectively, the frequency and intensity of the experience, and the other three to the degree of impairment the experience is causing (e.g., assessing to what extent anxiety/depression interferes with things one needs to do at work, school, or home, or with one’s social life and relationships).
Lastly, another important avenue for future research to gain a better understanding of the double-edged sword of loneliness, is to examine whether we can predict or detect when loneliness is evolving to its maladaptive side at an earlier stage to prevent further harm. For example, a signal that loneliness is becoming more maladaptive might be when it goes together with other factors, such as negative cognitive biases, self-defeating attribution styles, or low self-esteem (cf. Vanhalst et al., Citation2015, Citation2018; Vanhalst, Luyckx, et al., Citation2013). This latter view nicely aligns the theoretical rationales of the RAM model, and explicitly takes the perspective of a gradual change of loneliness becoming less adaptive with more and more maladaptive consequence the longer it endures. To our knowledge, no studies have yet explored whether asking such additional questions (e.g., on the impairment, causes, or future expectations of one’s loneliness experience) reveals relevant insights in the adaptive and maladaptive sides of loneliness.
Conclusion
In this review, we argued that the double-edged sword of loneliness – that is, its adaptive function versus its maladaptive consequences – has been interpreted and examined in very different ways. In general, the duration of loneliness has been used as an explaining factor, suggesting that short-term loneliness might result in increased attempts to regain social connection and therefore serves an adaptive function, whereas long-term loneliness might result in maladaptive health outcomes. More work is needed, however, on the theoretical as well as empirical level to fully understand how the duration of loneliness might explain the double-edged sword of loneliness. Specifically, it remains to be examined whether the duration should be conceptualized as a developmental process in the same experience or whether we should focus on a cut-off point for chronic loneliness, with clinical implications. Moreover, future work should disentangle the role of the duration, frequency and intensity of loneliness, and should examine factors that can be used to predict when and for whom loneliness is (becoming) maladaptive. Such insights will be crucial to better conceptualize and operationalize loneliness – to prevent both overpathologising and overlooking individuals in need of help.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability statement
Data sharing is not applicable to this article as no new data were created or analysed in this study.
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