Laughter elevates the levels of breast-milk melatonin

Patients with atopic eczema (AE) often complain of sleep disturbance. Melatonin is involved in sleep, and the levels of blood melatonin in patients with AE are decreased in comparison to healthy subjects. However, the levels of breast-milk melatonin had only been reported in healthy subjects. Laughter increased natural killer cell activity in blood and free radical-scavenging capacity in saliva in healthy subjects. Thus, the effect of laughter on the levels of breast-milk melatonin was studied in mothers with AE. Moreover, the effect of feeding with breast milk after laughter on allergic responses in infants was studied.

Forty-eight infants aged 5-6 months were enrolled. All of the infants had AE and were allergic to latex and house dust mite (HDM). Half (n=24) of the mothers of these infants were patients with AE, while another 24 mothers were healthy subjects. The mothers viewed either an 87-min humorous DVD (Modern Times, featuring Charlie Chaplin) or an 87-min nonhumorous weather information DVD at 2000 h. After viewing, breast milk was collected sequentially from 2200, 2400, 0200, 0400 to 0600 h. The levels of breast-milk melatonin were measured. In addition, skin wheal responses to HDM and histamine were studied in infants.

Laughter caused by viewing a humorous DVD increased the levels of breast-milk melatonin in both mothers with AE and healthy mothers. In addition, allergic responses to latex and HDM of infants were reduced by feeding with breast milk after laughter of mothers with AE or of healthy mothers.

Laughter increased the levels of breast-milk melatonin in both mothers with AE and healthy mothers, and feeding infants with increased levels of melatonin-containing milk reduced allergic responses in infants. Thus, laughter of mothers may be helpful in the treatment of infants with AE.