- Data are scarce with regard to risk factors for acute community-acquired alveolar pneumonia (CAAP) in children, but it is known that children with sleep-disordered breathing (SDB) experience more respiratory infections. We aimed to assess whether SDB is a risk factor for CAAP in early childhood. We conducted a prospective, nested, case-control study assessing children < 5 years old who had been given a diagnosis of CAAP based on World Health Organization radiographic criteria. Demographic and clinical data were collected. SDB symptoms were documented using a structured questionnaire. CAAP study and retrospective sleep laboratory databases were compared. SDB presence and severity were determined by questionnaire and polysomnography (PSG). A total of 14,913 children underwent chest radiography during the study period; 1,546 children with radiographically proven CAAP (58% boys) and 441 control subjects (54% boys) were prospectively enrolled. Frequent snoring was reported in 18.6% vs 2.9% subjects with CAAP and control subjects, respectively (P < .001). The respective figures for subjects with CAAP and control subjects for restless sleep, nocturnal breathing problems, abnormal behavior, and chronic rhinorrhea were 21.6% vs 5.3%, 5% vs 1.4%, 6.4% vs 0.2%, and 12.9% vs 1.8%, (P < .001 for each). Fifty children (3.3%) with CAAP vs three control subjects (0.7%) underwent adenoidectomy (P < .001). PSG diagnosis of obstructive sleep apnea had been established previously in 79 patients (5%) with CAAP vs six (1.3%) of the control subjects (OR, 3.7 [95% CI, 1.6-10.0]; P < .001), with higher severity in patients with CAAP than in control subjects. SDB is common in children with CAAP and is possibly a predisposing risk factor for CAAP in children < 5 years old. We recommend considering SDB in young children who are given a diagnosis of CAAP.