Difficulty in initiating and maintaining sleep associated with cow's milk allergy in infants.

To confirm that sleeplessness in infants can be related to an undiagnosed allergy to cow's milk proteins, 71 infants were studied. Group I consisted of 20 infants referred for chronic insomnia that had appeared in the early days of life. Group II was made up of 31 infants admitted for skin or digestive symptoms attributed to cow's milk intolerance; 13 of these infants were shown to sleep as poorly as the infants of group I. Group III consisted of 20 infants with no history of sleep disturbance or milk allergy. The three groups of infants were comparable for sex and age. Laboratory tests revealed immunologic reactions to milk in all the infants in groups I and II. The sleep of the insomniac infants (group I, and the 13 "poor sleepers" in group II) became normal after cow's milk was eliminated from the diet. Insomnia reappeared when the infants in group I were challenged with milk. We conclude that infants with clinically evident milk allergy may suffer from sleeplessness and that when no evident cause for a chronic insomnia can be found in an infant the possibility of milk allergy should be given serious consideration.