In a study published in the Journal of Psychosomatic Research, researchers have found out that breastfed babies with eczema showed milder allergy symptoms if their mothers laughed hours before feeding them.

[The researchers] showed breastfeeding mothers either a feature length charlie chaplin movie or bland footage of weather information, and took samples of breast milk at regular intervals afterwards. Two milk feeds later, he also measured their babies' allergic reactions to dust mites and latex. Those infants whose mothers had laughed had markedly reduced reactions (Journal of Psychosomatic Research, vol 62, p 699).

So, there; make it a habit to laugh (yes, despite your or your child's allergies). It does wonders in more ways than one!