Loneliness has been described as an aversive emotional state experienced when people's desire for social connection is not met. Loneliness is widespread — an estimated one in four adults in Australia feels lonely (Australian Psychological Society, 2018) and the rate has increased during the COVID-19 pandemic and related lockdowns and social distancing policies. While the experience of loneliness is considered to be universal (Barreto et al., Reference Barreto, Victor, Hammond, Eccles, Richins and Qualter2021), it is also implicated in the development and progression of a range of physical and mental health conditions (Park et al., Reference Park, Majeed, Gill, Tamura, Ho, Mansur and McIntyre2020) — as some papers in this collection help to demonstrate. Loneliness itself is not a diagnosable condition, which may explain why the availability of theoretical models and specific assessment and intervention options for loneliness has lagged those for other emotional states such as anxiety, depression, anger, and shame. As loneliness researchers from the disciplines of health, clinical, and music psychology, we have guest edited this collection of short reports to bring readers an update on the understanding, measurement, and intervention strategies to address loneliness in a range of populations and contexts.

There are seven papers in the collection. The first is a review and meta-analysis of studies examining the relationship between loneliness and depressive symptoms in children and adolescents (Dunn & Sicouri, Reference Dunn and Sicouri2022). This review included 44 studies published between 1983 and 2021, representing data from 27,214 participants aged 9–18 years. The review established an overall positive correlation between loneliness and depression of r = 0.48, which is consistent with earlier research on adult populations. Interestingly, participant gender and age did not moderate the strength of the relationship between loneliness and depression. The authors spoke of the potential role of health professionals in helping young people to feel part of a group, maintain the quality and quantity of their relationships and experience social rewards.

The second paper examined loneliness and sense of belonging in Australian university students, using a comparison of three cohorts of first year students entering a metropolitan university in 2019 (pre-COVID-19), 2020 (first wave of COVID), and 2021 (lifting of public health restrictions) (Dingle, Han, & Carlyle, Reference Dingle, Han and Carlyle2022). This study highlighted the detrimental social impact of COVID-19 and the associated rapid move to isolated online learning for university students in terms of increased loneliness and decreased sense of university belonging for students in the 2020 cohort. These social effects were strongly related to levels of psychological distress. The implications for health professionals and university staff are to help students to develop a sense of connection and belonging at university both in educational activities and in extra-curricular social activities.

The third and fourth papers focus on sensory aspects of loneliness such as touch and sound. For people who lived alone during COVID-19 long lockdowns, the absence of social touch was emphasised, and people spoke of a desire to hug their loved ones and to be physically close to other people again. Noone and McKenna-Plumley's (Reference Noone and McKenna-Plumley2022) narrative review argues that elements of presence, absence, and type of touch may impact upon loneliness experiences. Disentangling the relationship between loneliness and the presence/absence of wanted and unwanted touch is identified as a challenging but important avenue for future research, while practitioners are urged to consider the suitability of using touch in their work with lonely service users and clients. Meanwhile, Groarke et al. studied music listening behaviours of older adults in Northern Ireland while they were isolated during the COVID-19 pandemic. They found that these older adults used music to feel more positive and less negative emotions, and that music listening provided a form of ‘social surrogate’, providing company and reminders of social relationships and experiences (Groarke, MacCormac, McKenna-Plumley, & Graham-Wisener, Reference Groarke, MacCormac, McKenna-Plumley and Graham-Wisener2022), suggesting that self-directed music listening may be a cost-effective and accessible means of supporting isolated older adults.

As an aversive emotional state, it makes sense that loneliness is related to the use of specific emotion regulation strategies, yet research on this topic is particularly under-developed. Tan et al. analysed the extent to which the use of 12 emotion regulation strategies was related to experiences of loneliness or psychological distress. They found that both loneliness and distress were characterised by a low use of cognitive reappraisal and a high use of catastrophising, rumination, and self-blame. Behaviourally, both were characterised by a high use of withdrawal. However, loneliness was distinct from psychological distress in terms of a high use of expressive suppression, low use of acceptance, and less seeking of social support (Tan et al., Reference Tan, Mancini, Gross, Goldenberg, Badcock, Lim and Preece2022). These findings help psychologists to identify emotion regulation targets that are likely to help clients reporting loneliness.

The sixth and seventh papers in the collection focus on social aspects of loneliness. Evans, Cruwys, Cárdenas, Wu, and Cognian (Reference Evans, Cruwys, Cárdenas, Wu and Cognian2022) conducted a series of studies about the link between life transitions and loneliness. In two experimental studies and a nationwide community survey conducted during the COVID-19 lockdowns, these researchers demonstrated that it is not just upheaval and change that produces loneliness during life transitions, but also level of isolation from existing and new social groups that determines loneliness during such periods. This work contributes to the theoretical understanding of how isolating transitions increase loneliness. That is, isolating life transitions disrupted social identification processes — our psychological connection with our groups — which, in turn, increased loneliness. The final paper in this special issue examines the social determinants of loneliness during COVID-19 (Bower et al., Reference Bower, Lauria, Green, Boyle, Smout, Donohor-Bales and Teesson2022). This longitudinal study indicates that a broad range of variables at the individual, community, and societal levels work together to determine our experience of loneliness. Variables like gender, relationship status, income, and living situation, neighbourhood belongingness all the way through to state/territory of residence played a contributing role. These findings emphasise the multifaceted nature of loneliness. Health professionals need to assess and consider factors outside of the psychological lens if we are to help clients address and overcome loneliness and its associated negative health implications. The findings also align with recommendations in the Ending Loneliness Together in Australia white paper (Ending Loneliness Together, 2020).