Loneliness is associated with more fragmented sleep, a cross-sectional study of members of a communal society showed.
In two Hutterite colonies in South Dakota, each unit increase in loneliness score was accompanied by an 8% increase in sleep fragmentation (P=0.01), Lianne Kurina, PhD, of the University of Chicago, and colleagues reported online in Sleep.
There was no relationship, however, between loneliness and sleep duration.
The findings are consistent with a previous study of college students and "lend support to the hypothesis that sleep quality, at least as indexed by sleep fragmentation, may be one pathway through which feelings of social connectedness influence future health."
Previous studies have identified a relationship between loneliness or a lack of social connections to poorer physical and mental health. One possible reason for the link could be that lonely people do not sleep as well as others.
To explore the issue, Kurina and colleagues interviewed 95 adults (mean age 39.8) from two Hutterite colonies. The Hutterites are a communal group of Anabaptists tracing their roots to 16th century Europe, much as do the Mennonites and Amish. Members of the community share all resources, follow a similar daily schedule, and eat the same diet. Tobacco use is prohibited.
All of those characteristics remove the confounding influence of major socioeconomic and lifestyle variables, according to the researchers.
In addition to being interviewed about feelings of loneliness and symptoms of depression, anxiety, and stress, the study participants wore wrist actigraphs to measure sleep fragmentation and duration.
Loneliness was assessed with three questions about how often the participants felt they lack companionship, felt left out, and felt isolated from others.
In general, there were low levels of loneliness, depression, and anxiety in the community.
Nonetheless, the lonelier individuals were more likely to have higher levels of sleep fragmentation, after adjustment for age, sex, body mass index, sleep apnea risk, and negative affect (which encompassed depression, anxiety, and stress).
Further adjustment for sleep duration, objective measures of social connectedness, and alcohol consumption did not change the results.
Loneliness was not, however, associated with sleep duration or self-reported sleep quality or daytime sleepiness.
"From an evolutionary perspective, this finding makes sense; humans must have relied on a safe social surround to survive and thrive," Kurina and colleagues wrote. "The absence of a secure social environment results in perceptions of social isolation that, in turn, have been shown to increase vigilance for threat and to heighten feelings of vulnerability. This heightened vigilance may be manifested during the sleep period as greater restlessness or more fragmented sleep."
It is also possible that the relationship goes in the other direction, from more fragmented sleep to increasing social disconnectedness, the researchers said.
Although the direction of the association cannot be determined from a cross-sectional study, "it may be telling that sleep fragmentation is most strongly associated with feelings of social connection versus, for example, negative affect," they wrote. "If the effect were mainly from sleep to psychological symptoms, it is not obvious why the effect would be stronger for perceived connection than for negative affect."
The authors acknowledged some limitations of the study, including the lack of an assessment of caffeine consumption and the possibility that actigraphy could overestimate sleep duration when individuals are awake but sedentary.
The study was supported by grants from the NIH.
The authors reported that they had no conflicts of interest.
- Reviewed by Dori F. Zaleznik, MD Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner