UNIVERSITY PARK, Pa. — Loneliness may be harmful to our daily health, according to a new study led by researchers in the Penn State College of Health and Human Development and Center for Healthy Aging focused on understanding the subtleties of loneliness and how variations in daily feelings of loneliness effect short- and long-term well-being. The researchers said the work provides more evidence in support of the 2023 statement made by U.S. Surgeon General Vivek Murthy on the devastating impact of loneliness and isolation on physical health in the country, calling it a public health crisis.

The work, published in the journal Health Psychology, also brings more attention to different experiences of loneliness, a focus during June 10-16 for Loneliness Awareness Week. 

The long-term health consequences of loneliness and insufficient social connection include a 29% increased risk of heart disease, a 32% increased risk of stroke and a 50% increased risk of developing dementia in older adults, according to the surgeon general. People who frequently feel lonely are also more likely to develop depression and other mental health challenges, compared to people who rarely or never feel lonely.

In the current study, the researchers found that loneliness can lead to negative health symptoms for people even if they do not generally identify as lonely or typically experience loneliness. People who experience more temporary feelings of loneliness or have a lot of variability in their feelings of loneliness are likely to have daily health issues related to loneliness, including general fatigue, headaches and nausea.

The data represents 1,538 participants in the National Study of Daily Experiences (NSDE), one of the studies in the MacArthur Foundation Survey of Midlife in the United States. NSDE is led by David Almeida, professor of human development and family studies at Penn State and senior author on the paper. The current study focuses on loneliness in midlife, using data from respondents between the ages of 35 and 65. Prior research on loneliness largely focuses on adolescents and older adults, the researchers said.

NSDE participants engaged in telephone interviews that assessed their daily stress and mood for eight consecutive days. Respondents were asked to describe any stressful and/or positive situations they encountered and their feelings for each day, including whether they felt lonely and how often. They were also asked if they had physical symptoms that day, including general fatigue or headaches. These assessments were performed twice, 10 years apart. 

From this data, researchers found that when participants were less lonely on average, and on days when loneliness was lower than a person’s average, they had fewer and less severe physical health symptoms. Additionally, participants who were more stable in loneliness across the eight days had less severe physical health symptoms.

“These findings suggest that day-to-day dynamics of loneliness may be crucial in understanding and addressing the health effects of loneliness,” Almeida said. “Increasing feelings of social connection even for one day could result in fewer health symptoms on that day. Such a daily focus offers a manageable and hopeful micro-intervention for individuals living with loneliness.”

Dakota Witzel, a postdoctoral research fellow in the Center for Healthy Aging and the lead author on the paper, said the results suggest that closer attention should be paid to daily, more temporary feelings of loneliness. While sustained loneliness can contribute to the long-term health effects identified in the surgeon general’s advisory, these shorter, more variable instances of loneliness can produce shorter-term negative health symptoms.

“A lot of research is focused on loneliness being a binary trait — either you’re lonely or you’re not. But based on our own anecdotal lives, we know that’s not the case. Some days are worse than others — even some hours,” Witzel said. “If we can understand variations in daily loneliness, we can begin to understand how it affects our daily and long-term health.”

Karina Van Bogart, doctoral candidate in the Department of Biobehavioral Health at Penn State; Erin Harrington, assistant professor of cognition and cognitive development at the University of Wyoming; and Shelbie Turner, postdoctoral fellow in the Division of Geriatrics and Palliative Medicine at Weill Cornell Medicine, also contributed to this research.

The National Institutes of Health funded this research.