Loneliness has had a tough run of late, with a growing body of research blaming it for everything from high blood pressure to heart disease to depression and cognitive decline. The research group of John Cacioppo, director of the Center for Cognitive and Social Neuroscience at the University of Chicago, has been among the leaders in leveling these medical charges against loneliness. But one missing piece of the puzzle remains – what biological mechanism connects a person’s feelings of inadequate social contact with the negative health outcomes? A new collaboration with epidemiologists and geneticists at the Medical Center suggest that the missing link might be in the bedroom.
For decades, professor of human genetics Carole Ober has studied a unique society called the Hutterites [pdf]. A religious group that originated in the 16th century, the Hutterites have formed several communal farms in the United States where some 150 people live and work together. The stability and isolation of the Hutterites make them a perfect population for studying the interplay between genes, environment, and disease – the mission of Ober’s research. Those qualities also made them the perfect group of people for a team lead by Lianne Kurina, assistant professor of epidemiology in the University of Chicago Department of Health Studies, to test the link between loneliness and sleep quality.
The new study, which appears in the journal Sleep, is not the first to examine this connection. A 2002 study led by Cacioppo used the most accessible pool of subjects on a college campus – college students – and found that those who scored higher on a psychological loneliness test displayed reduced sleep “efficiency” with no change in sleep duration. In other words, the loneliest subjects slept just as long as their socially satisfied peers, but suffered more “microawakenings” and lower sleep quality.
Because college students reflect only a narrow band of society, it was important to replicate the result in an entirely different population. Enter the Hutterites, who were also tested using a loneliness scale and asked to wear wristband sleep monitors to track their activity during sleep. Because of their communal lifestyle, even the loneliest Hutterites were less lonely than the general population. But the same correlation was detected between loneliness and sleep quality – for each point increase on the loneliness scale used to test the subjects’ social feelings, the researchers observed an 8 percent increase in sleep fragmentation. Furthermore, the lonelier Hutterites did not themselves report poor sleep or daytime sleepiness, indicating that the effects are mostly subconscious.
“Loneliness has been associated with adverse effects on health,” Kurina said in a press release. “We wanted to explore one potential pathway for this, the theory that sleep – a key behavior to staying healthy – could be compromised by feelings of loneliness. What we found was that loneliness does not appear to change the total amount of sleep in individuals, but awakens them more times during the night.”
The evidence is still not strong enough to conclusively place sleep deficits as the intermediary between loneliness and poor health. As the paper admits, the opposite relationship could be true: sleep fragmentation could increase feelings of social disconnection. But a flood of recent evidence, much of it from the University of Chicago Sleep, Metabolism, and Health Center, suggests that the third of each day we spend sleeping can dramatically affect several different aspects of our health, including diabetes, obesity, dieting success, and testosterone levels. Certainly, the newly replicated connection between a lonely heart and restless nights offers an intriguing theory for future study.
But why would feelings of social inadequacy disrupt a person’s time in bed?
The paper proposes an interesting theory rooted in the evolution of early human behavior, where group living was necessary to defend against the dangers of the wild world. If one of those prehistoric humans found themselves forced to spend the night alone, a deep sleep would have left them open to attack. Hence, loneliness may have been originally linked with restless sleep as a survival measure, and thus hard-wired into our genes.
“Whether you’re a young student at a major university or an older adult living in a rural community, we may all be dependent on feeling secure in our social environment in order to sleep soundly,” Kurina said. “The results from these studies could further our understanding of how social and psychological factors ‘get under the skin’ and affect health.”
(Image: Carlo Naya (1822-1881) – “Carpaccio, V., Detail from the Dream of Saint Ursula (the head of the Saint). – Accademia, Venice”. From Wikimedia Commons)
Kurina, L., Knutson, K., Hawkley, L., Cacioppo, J., Lauderdale, D., & Ober, C. (2011). Loneliness Is Associated with Sleep Fragmentation in a Communal Society SLEEP DOI: 10.5665/sleep.1390