(Health.com) -- Feeling isolated and disconnected from the people around you may keep you from getting a good night's sleep, even if you're not aware of it, a small new study suggests.
People who feel lonely tend to experience more nighttime restlessness and disruptions than their better-adjusted peers, the study found, which may partly explain why loneliness has been associated with health problems such as high blood pressure, heart disease, and depression, says lead researcher Lianne Kurina, Ph.D., an assistant professor of epidemiology at the University of Chicago.
"In lab experiments, when people are intentionally woken up repeatedly, it seems to have effects on [their] metabolism," she says. "Their insulin sensitivity goes down, almost suggesting that poor sleep could put them at higher risk of type 2 diabetes, for example."
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In the new study, published today in the journal Sleep, the link between loneliness and sleep disruptions persisted even after the researchers took into account marital status and family size. This finding underscores an important distinction between loneliness and social isolation, Kurina says: The amount of loneliness people feel ultimately depends on how they perceive their social situation, not the situation per se.
"There can be people with lots of social connections that feel terribly alone, and conversely there are people with relatively small social networks who do just fine," Kurina says. "Different people have different needs in terms of relationships -- and it's the space between what you want and what you have that can turn into loneliness."
The 95 participants in the study all had strong social connections, as they were part of a close-knit, rural community in South Dakota. Yet even small differences in their degrees of loneliness had an impact on their sleep.
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Kurina and her colleagues asked the participants how often they felt a lack of companionship, left out, or isolated from others, and they used these responses to rate the men and women on a standard loneliness scale. Then, for one week, the participants wore a wrist device to bed each night that records body movement and sleep disruption (known as an actigraph).
Each one-point increase in the loneliness scale was associated with about an 8% increase in sleep disruptions and restlessness, the researchers found, even when they controlled for age, sex, body mass index, the breathing disorder known as sleep apnea, and negative emotions such as depression, anxiety, and stress.
Loneliness did not appear to influence sleep quality or daytime sleepiness, however, which suggests that the sleep disruptions were minor. More research will be needed to determine if these low-level disruptions can have effects on health similar to those seen in experiments when volunteers are woken up, but it seems plausible that comparable health consequences could occur, Kurina says.
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It makes sense that someone who feels alone and vulnerable may wake more easily throughout the night, since early humans may have evolved this tendency to protect against potential threats, the study notes. Even now, Kurina says, short-term feelings of loneliness can be healthy because they can encourage humans to make social connections. Problems can arise, however, if loneliness becomes chronic.
"People who have been very lonely for a while start to expect rejection, to the point where it can become a self-fulfilling prophecy," Kurina says. For this reason, she adds, it isn't always helpful to tell someone who feels isolated and insecure to just make friends, get a pet, or go on more dates.
So what's a lonely heart to do? Begin to rebuild social connections in an emotionally safe way, Kurina suggests. "Engage in situations where you're not necessarily expecting people to give to you, but where you're the one giving -- like volunteering, or common-interest meetings like book groups," she says. "Slowly you'll begin to see the world -- and see your relationships -- in a more positive way."
