Loneliness could be bad for your health, psychologists in the US have warned.

University of Chicago psychologists Louise Hawkley and John Cacioppo studied both a group of college-age individuals and adults aged 50-plus to reach the conclusion.

When the psychologists looked at the lives of the middle-aged people in their study, they found that although the lonely ones reported the same number of stressful life events, they identified more sources of chronic stress and recalled more childhood adversity.

When faced with similar challenges, the lonelier people appeared more helpless and threatened. And ironically, they were less apt to actively seek help when stressed out.

The psychologists took urine samples from both the lonely and the more contented volunteers, and found that the lonely ones had more of the hormone epinephrine flowing in their bodies.

Epinephrine is one of the body’s “fight or flight” chemicals, and high levels indicate that lonely people go through life in a heightened state of arousal, reported online science portal, EurekAlert.

As with blood pressure, this physiological toll likely becomes more apparent with aging.

Since the body’s stress hormones are intricately involved in fighting inflammation and infection, it appears that loneliness contributes to the wear and tear of aging through this pathway as well.

When people experience stress, their bodies normally rely on restorative processes like sleep to heal.

But when the researchers monitored the younger volunteers’ sleep, they found that their lonely nights were disturbed by many “micro awakenings.”

The findings of the study appeared in last month’s issue of Current Directions in Psychological Science, a journal of the Association for Psychological Science.

The researchers, however clarified that loneliness is not the same as solitude. Some people are just fine with being alone, and some even see solitude as an important path to spiritual growth.