Do Single People Age Faster? The Answer May Lie in Sleep

Jie-Yu Chuang^*

• Columbia University, New York City, New York, United States

Roman&c rela&onship quality has been related to physical health, mental health, diet and physical ac&vity (1). Indeed, it would be op&mal to have a suppor&ng roman&c rela&onship. However, global marriage rate is declining (h@ps://ourworldindata.org/marriages-and-divorces). Furthermore, infidelity in roman&c rela&onship is also increasing. Back in the year 2000, only about 8% of Chinese people were sexually unfaithful to their partners whereas by 2015, this rate had jumped to more than 24% (2). Evolu&onarily speaking, how does this trend of subpar roman&c rela&onship impact on human species? Moreover, will subpar roman&c rela&onship affect human popula&on health or even longevity? Although not receiving much a@en&on in previous researchers, the influence of roman&c rela&onship on aging is an important considera&on (1). Despite the widely acclaimed benefits of being single, a significant body of research has supported the link between sa&sfactory roman&c rela&onship and successful aging. In 1858, the famous epidemiologist William Farr suggested the longevity advantage of marriage in French men (3). A recent longitudinal study (N=7641) indicates men who were con&nuously married aged more successfully (physical wellness, mental wellness, social wellness, and self-rated wellness) than their never-married counterparts (4). Furthermore, another longitudinal study (N=974) with par&cipants reported their roman&c status at four phases (age 26, 32, 38 and 45) points to the associa&on between slower biological aging (19 biomarkers and facial aging) and high-quality roman&c rela&onship in both men and women (5). Marriage was also found to be associated with a slower epigene&c aging (6). Nevertheless, the rela&onship between roman&c rela&onship status and aging is complex. Singlehood has not been consistently associated with accelerated aging. Using data from the 2016 US Health and Re&rement Study (aged 50-100, N=3765), Yu et al. failed to find prominent epigene&c aging difference between single and married people acer controlling for sociodemographic characteris&cs, economic resources, depressive symptoms, and health behaviors (7). Furthermore, if marriage does indeed slower aging process, what is the underlying mechanism? A secure roman&c rela&onship, rooted in a@achment theory, may foster a sense of security, elevate Oxytocin levels, thereby mi&ga&ng the stress response and bolstering immune func&on (8). However, recent study failed to iden&fy significant difference in mental and physical health between single and married popula&on (9). Another study found that the odds ra&o of mee&ng the WHO physical ac&vity recommenda&ons was 40% higher in single than in married par&cipants (10). Presumably, poten&al moderators or confounders in the rela&onship between marriage and aging should be considered. Overall mental wellbeing has been shown to have a more prominent impact (1.65 years) on biological aging than the marital status (0.59 years) alone (11). Indeed, researchers have found that with increasing age, having a partner is less predic&ve of psychological health and the sa&sfac&on with being single increased (12). Among all psychological factors, subjec&ve quality of sleep (0.44 years) has the largest impact on aging (11). Moreover, a recent large cohort study (N=589) suggests an associa&on between poor sleep quality and accelerated brain aging, even in midlife (13). In a sample of 154 middle-aged to older adults, it has been found that decelerated cellular aging (represented by telomere length) is associated with be@er sleep quality (assessed via Pi@sburgh Sleep Quality Index) (14) . Irrespec&ve of marital status, sharing a bed with a partner has been linked with be@er sleep quality (15). Indeed, being married alone does not guarantee a good sleep quality since sleep quality was found to be correlated with couple rela&onship quality in a meta-analysis (16). No significant difference in sleep quality was found between married and single U.S. (17) and Japanese people (18). Consequently, based on the scien&fic evidence, sleep quality may act as an unaddressed mediator in the intricate rela&onship between marriage status and aging. As global trends indicate a staggering increase in both singlehood and the aging popula&on, further comprehensive research is impera&ve and warranted to thoroughly inves&gate the complex interplay between aging and the dynamics of roman&c rela&onships. Mental wellbeing, especially subjec&ve sleep quality, was found to be significantly associated with aging. Based on current evidence, subjec&ve sleep quality can be assumed to moderate the rela&onship between marital status and aging. Future research should explore the interplay between subjec&ve and objec&ve sleep quality, biological aging, and marital status, alongside other mental and physical health indicators, poten&ally through a prospec&ve cohort study. If, as predicted, sleep quality is the most pivotal factor media&ng the rela&onship between marital status and aging, individuals without partners can s&ll decelerate aging process through improvement of sleep quality. In addi&on to general strategies to improve sleep hygiene (i.e., keep a consistent sleep schedule), specific interven&ons tailored to this singlehood-sleep quality-aging pathway could be explored and inves&gated to op&mize sleep quality and mi&gate aging in single individuals. Examples may include: sleeping with a soothing stuffed toy or sleeping with an ar&ficial intelligence (A.I.) voice companion. Future studies are warranted to find the most effec&ve strategy. Oscar Wilde, the world-renowned Irish poet once said "To love oneself is the beginning of a lifelong romance." Indeed, even amidst the trend of singlehood and popula&on aging, we can s&ll embrace the journey of self-love and find romance in the pursuit of health and youth. Furthermore, the secret to the fountain of youth might be sleep.