Intimacy with a romantic partner linked to important processes in the body

Staying with a romantic partner can help the body regulate blood sugar, skin temperature, and the effects of stress with less effort than alone. In four experiments with adults and infants, participants experienced less stress and recovered more quickly during trials accompanied by a loved one, suggesting that social connections support basic biological functions.

“Humans are deeply social, but physiology is usually studied as if the body regulates itself in isolation,” said Shir Atzil. Social animals begin to depend on others to regulate their physiological needs.

To test, they studied an automatic system that humans do not consciously control. The regulation of blood sugar after carbohydrates meets the criteria. The researchers conducted a study with mothers and infants, followed by three pre-recorded experiments with adults. Efficiency was measured by how far the signal deviated from the baseline and how long it took to return to normal; combining height and duration into a single score allowed for a comparison of effort alone and with a partner.

In the first experiment, 108 participants (54 pairs) ate 102 grams of white bread (50 grams of carbohydrates) once alone, another with a partner, and a blood test tracked glucose for two hours. The bursts were smaller and faster when taken together: the total level of the same people was on average 14.55% lower, and when comparing the first sessions – 23.9% lower.

“The effect was significant for a single meal,” said Atzil. Some received much more, some received less.

To find out whether the presence of a partner simply reduces stress, electrodermal activity was monitored. Conduction decreased below baseline during the test, not increased. Consideration of conductivity or touch left the partner's advantage unchanged.

In the third experiment, 115 adults (57 pairs) received two short shocks while their skin conduction was recorded. When comparing the first sessions, arousal in the presence of a partner was 5.98 percent lower than in solitude, although a decrease of 1.89 percent in the same people with repeated sessions was not significant. When all 339 observations were combined, total costs were 7.59 percent lower in individuals and 12.07 percent lower in groups in social settings. The pattern persisted after taking into account relationship satisfaction, BMI, time of day and order of classes, although some participants showed less effective regulation with a partner.

"I hypothesized the effects of glucose in a 2018 paper, but the fact that we observed social physiology across all systems was overwhelming," the researchers concluded. The same pattern manifested itself in temperature regulation and stress. If staying with a partner day after day improves the regulation of several systems, over time, this can lead to a decrease in the overall load on the body.”.