One study done on pre-term infants (Field, International Journal of Behavioral Development, 22(4),1998) found that the stimulation of pressure receptors under the skin caused an increase in vagal nerve activity and slowing physiology that then caused the babies to be more relaxed in their behaviors. This also led to a decrease in stress hormones, most particularly cortisol, and an increase in immune function, particularly natural killer cells. The take home point again is that TOUCH MATTERS. Babies do better when they are touched, as do we all.
Another interesting study in the Journal of Behav Med. 2003 Fall;29(3) by Grewen, Anderson, Girdler and Ligth showed that loving partner contact is related to lower cardiovascular reactivity. This was measured by blood pressure reactivity to stress in healthy adults. The stress was induced by asking people to do a public speech (one of the most common fears!). Half of the participants had been able to hold their partners hand for 10 minutes prior to the speech and also asked to hug their partner for 20 seconds. The other half were just asked to sit by themselves for 10 minutes. People who had the loving contact of their partner prior to the stress had less increases in BP. The authors concluded that "These findings suggest that affectionate relationships with a supportive partner may contribute to lower reactivity to stressful life events and may partially mediate the benefit of marital support on better cardiovascular health."
Another study done by Grewen, Girdler, Amico and Light (Psychosomatic Medicine, 67, 2005) found that people's opinions about how supportive their partners are can be measured by looking at oxytocin, norepinephrine, cortisol in the blood as well as actual blood pressure before and after loving contact with their partner. Couples were assigned to 10 minutes of loving contact and then their blood was analyzed. Those who rated their relationship as more supportive had higher levels of oxytocin and in women higher partner support was correlated with lower BP. For women higher levels of oxytocin were also related to lower BP and lower levels of norepinephrine. The authors conclude that "Greater partner support is linked to higher [oxytocin] for both men and women; however, the importance of [oxytocin] and its potentially cardio-protective effects on sympathetic activity and BP may be greater for women." Again it is important to note that this study essentially measures the effects of physical contact with a loving partner, showing that loving touch in a supportive relationship literally affects our body chemistry in beneficial ways.
This link between loving touch and oxytocin lead to Dr. Zak prescribes at least 8 hugs per day in his TED talk in order to feel happier and more connected, as well as to nurture relationships. Zak's talk discusses the findings of the research above on hugging one's partner and how it can benefit one's health, especially the cardiovascular system.
In the wake of Valentines's Day it seems appropriate to celebrate the importance of loving touch. Perhaps science has finally given us reasons to stop feeling guilty about our inherent interdependence. It's time to support our need for connection and quit literally embrace our need for others. My advice is to love well and touch often. Your heart, immune system, stress level and state of mind will thank you.
With warm wishes,