The study aimed at evaluating possible associations between snoring and/or noisy breathing in sleep and daytime behaviour in 2-4-month-old infants using the Early Infancy Temperament Questionnaire (EITQ) as a tool. It covered the period from 1997 to 1998 and comprised 200 randomly selected clinically healthy infants aged 2-4 months from the community who were singletons and born in St. Petersburg within the chosen period. The mothers were asked to complete the questionnaires addressing infant, maternal, and major demographic characteristics, some infant care practices as well as the infant's habitual breathing symptoms during sleep. As a part of interview, the mothers answered the EITQ consisting of 76 items which describe different aspects of infant behaviour. Groups of questions were added according to a scoring sheet to produce total scores describing nine different aspects of infant temperament: activity, rhythm, approach, adaptability, intensity, mood, persistence, distractibility and threshold. In 129 cases (64.5%), mothers reported no respiratory disturbances during sleep in their infants. Mothers of ten infants (5.0%) described their babies as habitual snorers; 48 babies (24.0%) were characterised as having other than snoring noisy breathing during sleep, and 13 (6.5%) habitually had both snoring and noisy breathing. Symptomatic infants were rated as being moodier when awake compared with asymptomatic ones and most moodiness was the feature of those infants who had both snoring and noisy breathing during sleep. These associations remained after adjustment had been made for major potential confounders.
Snoring and noisy breathing during sleep, rather common symptoms in young infants, may be associated with specific behavioural disturbances, and moody infants should be investigated carefully for possible obscure respiratory problems.