This research comes from Carnegie Mellon University, so it must be good, right? 
In these days, as the cracks in our system of scientific funding, research, reviewing, and reporting are becoming evident, it's nice to find results I can embrace wholeheartedly.
In a carefully controlled laboratory at Carnegie Mellon University, researchers exposed more than 400 healthy volunteers to the common cold virus. However, before the viral exposure, researchers spent two weeks meticulously tracking something most scientists might overlook: whether the participants had been hugged each day. ... Participants who were hugged on most days had about 60 percent lower odds of becoming infected than those who were rarely hugged. Additionally, those who did get sick recovered more quickly and had stronger immune responses than those who received fewer hugs.
When we hug someone, a cascade of events unfolds in our bodies and brains, affecting us on multiple levels—neurobiological, neurochemical, and social. Neurobiologically, hugging stimulates a network of sensory nerves under the skin, particularly a specialized group called C-tactile afferents, sometimes referred to as “cuddle nerves.” ... When triggered, cuddle nerves also release endorphins, the body’s natural painkillers that help boost mood. ... On a neurochemical level, hugging triggers the release of several “feel-good” chemicals. Chief among these is oxytocin ... which enhances feelings of bonding, trust, and safety. In addition, hugging releases dopamine, which is associated with pleasure, and serotonin, which stabilizes mood and promotes happiness. From a social and psychological standpoint, hugs convey support without the need for words, serving as nonverbal affirmations of shared emotion, reinforcing social bonds.
Hug duration was also considered in the study.
When researchers tested different types of hug styles and durations, they discovered precise requirements: one-second hugs felt unsatisfying and provided minimal benefit. At the same time, five to 10 seconds proved optimal before longer contact became uncomfortable. For intimate relationships, 20-second embraces produce the strongest measurable effects.
The article does not specifically mention one vital category of hugs: those between parents and their young children. (And grandma hugs! Never forget the regenerative power of grandma hugs!) Possibly it was included in the "intimate relationships" category, but I'm inclined to suspect that there were not enough people in the parent/child cohort for meaningful data. Many university studies are done on their captive audience of college students; I'd like to know the demographics of their volunteers.
Read the whole article for more, including previous studies. Here's one from 2003:
Couples who had 10 minutes of hand holding followed by a 20-second hug with their partner before giving a speech had lower blood pressure and heart rate by half compared with those who sat quietly without contact. These results suggest that affectionate touch provides physiological protection, which partially explains the heart health benefits associated with supportive relationships.
Are you a bit short on the opportunity for hugs in your life? Do not despair!
Regular affectionate contact produces benefits that extend far beyond stress reduction and a healthier heart. People who receive consistent physical comfort—whether from humans, pets, or even weighted blankets—sleep more soundly and wake more refreshed than those lacking such contact.
