We all know that a hug from a loved one can bring a surge of good feeling. But did you know that researchers in Japan put it to the test?
In a 2009 paper titled 'Profiling of serum proteins influenced by warm partner contact in health couples' in the journal Neuroendocrinology Letters, the researchers describe the results of experiments where they asked couples to evaluate their emotions as they "freely hugged and kissed" their romantic partner, and they also measured levels of proteins in their blood serum.
The participants reported becoming “happier and less irritated after kissing and hugging” (which you might expect) and there was an increase in proteins called serum albumin and beta2-microglobulin.
“These results suggest that psychological stress may be reduced and we may feel happiness when we kiss and hug a romantic partner,” write the authors. “Furthermore, these results also suggest that warm partner contact influences peripheral circulating proteins, more importantly, may promote health and wellbeing.”