Funnel chest or pectus excavatum (PE) is a chest wall deformity, and its major causes include hereditary connective tissue disorders and neuromuscular diseases [1,2]. In addition, PE is more likely to occur in the context of disorders associated with upper airway obstruction, including adenotonsillar hypertrophy and bronchomalacia [3], suggesting that these are potential causes of PE. Indeed, repeated increased intrathoracic negative pressure swings in children with sleep apnoea could lead to PE, although only limited evidence exists to this effect. We hypothesised that sleep-related breathing disorders (SRBDs) is among the causes of PE in children, and therefore examined the association between PE and SRDBs in children.As part of the Matsuyama Children's Study, which was conducted between 1 October 2014 and 31 March 2015 [4,5], a questionnaire was distributed to the caregivers of all 25 000 school children in Matsuyama City, Japan. Children at high risk for SRBDs were reported as having at least one of the following sleep-related manifestations, including disrupted breathing for two to seven nights a week, struggling to breathe at night for two to seven nights a week, snoring for five to seven nights a week, suddenly falling asleep for three to seven nights a week, or loud snoring for two to seven nights a week, or parental serious concerns on their child breathing during sleep conditions for two to seven nights a week. A total of 1752 children, which included all those children at high risk for SRBDs, were invited for a detailed interview and physical work-up.