Table 2.

Summary of cross-temporal meta-analyses on historical changes in loneliness levels

Study	Age group	Country	Loneliness measure	Time period	Loneliness trend	Effect size for mean-level change across the entire time period
Buecker et al. (2021)54	Emerging adults (18–29 years old)	Studies from all continents, but mostly from the USA	Different versions of the UCLA Loneliness Scale163,164	1976–2019	Significant increase in loneliness only in North American samples, not in European or Asian samples (possibly owing to lack of statistical power). No significant differences in historical changes in loneliness between North American and European and Asian samples. Values have been relatively stable since 2012.	d = 0.56
Clark et al. (2015)52	High-school students (Study 1)	USA	Revised UCLA Loneliness Scale164	1978–2009	Loneliness declined	d = –0.26
	College students (Study 2)	USA	Six items with five response options	1991–2012	Loneliness declined	d = –0.11
Xin & Xin (2016)53	College students	China	Chinese version of the UCLA Loneliness Scale (Version 3)163,165	2002–2011	Loneliness increased	d = 0.39
Yan et al. (2014)55	>60 years old	China	Chinese version of the UCLA Loneliness Scale (Version 3)163,165	1995–2011	Loneliness increased	d = 1.02