Editor,—Rona et al 1 have related sleep disturbance to sociocultural factors associated with ethnicity and respiratory illness and concluded that these are important risk factors for sleeping disorders in childhood. We have recently completed a study examining the relation between nighttime cough and sleep in inner city children,2 and found that although there is an association, it is very weak (regression coefficient 0.13, SE 0.036). Of 96 subjects eligible for the …