The Price Of Loneliness Is Sleep, Not Only In Twins

Scientists have found a connection between loneliness and sleep disorders in adolescents. One group, in particular, was at risk. 

Humans are social beings. If they are lonely, it not only feels bad, but their health also suffers. Loneliness, as various studies have shown, can be associated with high blood pressure, depression, or weight problems, for example.  However, researchers have observed most of these phenomena in older people in particular. The extent of the correlation in young people is less well understood.

It is known that the feeling of loneliness is not uncommon, especially among young people. According to a report by the Mental Health Foundation (1), loneliness is most common among people between the ages of 18 and 34. London scientists have now uncovered a connection among young people: according to the study published in the journal Psychological Medicine (2), lonely young people suffer somewhat more from sleep problems than their peers who do not think they are lonely.

By loneliness, scientists do not mean being alone. Because also humans, who have only comparatively little contact to others, can be lucky and content. Conversely, some people feel lonely although they are actually surrounded by many people. By loneliness, researchers mean a stressful feeling of being abandoned and unloved by the world. And even when you have something like a social life, it feels inadequate and unfulfilling.

To find out what influence this feeling has on young people’s sleep at night, the scientists at the London King’s Collage investigated 2232 twins between the ages of 18 and 19 through interviews and questionnaires: How often do you lack company with others? How often do you feel excluded or left alone? How often do you feel isolated from others? Finally, how often do you feel alone? In addition, the scientists monitored the sleep quality of their volunteers over a period of one month. For example, they were interested in how long it takes for the test persons to fall asleep, how long they sleep, how often they wake up, and how well they feel the next day.

Slightly more than a quarter of the test persons stated that they sometimes felt lonely. Another five percent regularly felt quite alone. The lonely teenagers had a 24 percent higher risk of fatigue and concentration difficulties during the day than the twins, who did not feel lonely. The connection persisted even when scientists excluded mental illnesses such as depression or anxiety because these conditions are often associated with sleep disorders. Professor Louise Arseneault of the Institute of Psychiatry, Psychology and Neuroscience (IoPPN) at King’s College London stated that reduced sleep quality is one of many ways for loneliness to get under the skin. Since several identical twins participated in the study, whose genetic make-up is almost identical by nature, the scientists were also able to examine the role played by the genes. However, the genetic material, as the study shows, probably does not seem to be the culprit.

One possible explanation for the connection between loneliness and poor sleep quality for the scientists is rather that lonely people feel less secure. Those who are separated from their social group are, after all, an easier prey in purely evolutionary terms. This perceived discomfort may lead to a stress reaction that disturbs sleep. From earlier studies (3), for example, there are indications that loneliness is associated with a changed amount of circulating cortisol, an important player in the body’s stress system. Violence that has already been experienced could reinforce this connection.

The scientists, therefore, examined which of the test persons had already experienced violence or abuse by family members or peers. In fact, it was found that the connection between sleep disorders and loneliness was much stronger in subjects who experienced particularly severe forms of violence and abuse.

“It is important to realize that loneliness in some people interacts with existing vulnerabilities,” says Timothy Matthews of IoPPN at King’s College London. “These people should receive support tailored to their needs,”—  at least if other studies can confirm these initial indications from the scientists.

This is part 27 of a series covering twin health provided by Paul Enck from the Tübingen University Hospital and science writer Nicole Simon. Further studies in twin research can be found at TwinHealth website. Translation was done with the assistance of DeepL translator.


  1. Griffin J. The Lonely Society? Mental Health Foundation, London, U.K. last accessed Sept 22, 2018,
  2. Matthews T, Danese A, Gregory AM, Caspi A, Moffitt TE, Arseneault L. Sleeping with one eye open: loneliness and sleep quality in young adults. Psychol Med. 2017 Sep;47:2177-86.
  3. Doane LD, Adam EK. Loneliness and cortisol: momentary, day-to-day, and trait associations. Psychoneuroendocrinology. 2010 Apr;35:430-41.