Dr Laura GinesiDr Laura Ginesi, Applied Physiologist at Birmingham City University’s Faculty of Health

Since its Valentine’s Day, I thought it would be appropriate to discuss the physiological aspects of kissing and the ways in which it serves for communication, a building block for intimacy and the good and bad effects it can have on our health and well-being.

The good

Some facts to get you started:

  • A one-minute kiss increases your metabolic rate. Estimates vary from 1-2 calories to burning 20-30 calories.
  • 34 facial muscles and 112 postural muscles are used during a kiss.
  • Two-thirds of people seem to kiss by turning their head to the right.
  • Your mouth is the most expressive feature of your face.
  • Affection in general and kissing in particular results in a reduction in perceived stress levels and improved relationship satisfaction.

Kissing can convey affection, attraction and love on the way to forming sustaining, loving relationships. It may be viewed by some as a spiritual connection – possibly even more intimate than sexual intercourse – because focusing on kissing can increase levels of arousal.

Depending on whom you are kissing, the reward pathway and pleasure centers of your brain respond with a feeling of excitement and surprise. You may find your heart racing; you’re feeling a bit breathless, the pupils of your eyes dilate a little and you may even feel a little sweaty? It’s not just in your mind! Humans seem to have developed an especially pleasant physical reaction to kissing and being kissed.

When you are kissing someone, you’ve entered his or her personal space. A passionate kiss locks two humans together – an opportunity to exchange scents textures, emotions and more. Lips and tongue are filled with very sensitive nerve endings. In evolutionary terms, these nerve endings are essential for our survival; immediately after birth, the rooting reflex directs a new-born baby towards his/her mother’s breast for milk and probably helped our ancestors to discern whether food was poisonous or not.

The bad

As thrilling as kissing can be, however, it can also be nasty or even dangerous; there can be extensive saliva exchange involved in ‘deep kissing’, which is likely to increase the risk of oral transmission of various bacteria and viruses and after an evening out, the grim reality of saliva, mouthfuls of partially eaten food and, sometimes, vomit, stale cigarette smoke, garlic, onions and alcohol may put potential partners off!

The ugly

Kissing is considered one way to transmit some sexually transmitted diseases and the average open-mouthed kiss can transfer around 250 colonies of bacteria. Here are some examples:

  • Herpes simplex virus 1 (HSV1) – causes cold sores.
  • Streptococcus, which can cause an array of infections, including gum disease.
  • Syphilis – the spirochaete is able to pass through intact mucous membranes or compromised skin.
  • and possibly best known of all ‘the kissing disease’ – Glandular fever (infectious mononucleosis, IM) is caused by the Epstein-Barr virus (EBV). It can be passed from person to person by close contact; kissing is an obvious means of transmission but the virus also spreads via airborne droplets, sharing of cups, toothbrushes. EBV can affect people of all ages, but glandular fever is most common in young adults and teenagers.

But don’t let these put you off puckering up with your loved one this Valentine’s day! By exchanging bacteria with your kissing partner you may actually be enhancing your immune system because it responds by making antibodies that may help to protect you in the long run – and let’s be honest a kiss or hug with that special someone really does make you feel better.

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Laura Ginesi

Laura Ginesi

Lecturer in Applied Human Physiology at Birmingham City University’s Faculty of Health
Laura Ginesi

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