We read with interest the paper by Douglas and coworkers (July 1993;48,719-21) on the possible inheritance of sleep disturbed breathing. Investigating 40 first degree relatives of patients with sleep apnoeas, they found a high prevalence of sleep apnoeas/ hypopnoeas (25%), several times higher than the prevalence in a random sample of the British population (5%).' The authors concluded that a familial predisposition to sleep apnoeas/hypopnoeas is probable. If such a predisposition is

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... , so must be the first stage of the syndromethat is, habitual snoring.2 To test this hypothesis we analysed the results of a questionnaire survey completed in a centre of preventive medicine in north east France. The parents of children aged four to 12 years who attended this centre in August and September 1990 answered a physician administered questionnaire on sleeping habits, and personal and familial medical history. Complete data were obtained from 487 children (51% girls), 30 of whom (6-2%) snored habitually. In univariate analysis habitual snoring was associated with a history of mouth breathing, habitual snoring in a family member, a personal history of allergy, hypermotility during sleep, enuresis, and a history of recurrent "colds". Strong further associations with a history of laboured breathing during sleep, stopping breathing during sleep, and night sweating could not be interpreted as the number of subjects was too limited. When these variables were entered in a multiple logistic regression procedure mouth breathing (X2= 16 9, p<00001), snoring by a family member (X2=5-1, p = 0-02), and enuresis (X2 = 48, p = 003) emerged as factors independently significantly associated with habitual snoring. In as much as mouth breathing is a clinical correlate of upper airway obstruction and enuresis a consequence of sleep disruption, habitual snoring by a family member appears as the main risk factor for snoring in this study. We believe our results are in favour of a "familial factor" for habitual snoring, as suggested by Douglas et al.