ABSTRACT.Nineteen adults with Down's syndrome were studied with the static charge sensitive bed (SCSBl method. A single whole‐night recording was made of each subject. Two different periodic breathing indices (PBIf and PBI%) were calculated from a computerized analysis of these recordings. A polygraphic recording was also made of one subject, a 52‐year‐old male. The EEC, the EOG, the EMG, nasal and oral airflow, and diaphragmatic movement were recorded, the latter with an abdominal strain gauge and with the SCSB‐method simultaneously. Good correlation was found between the recording with the SCSB and the strain gauge. The apnoea index (AI calculated from the polygraphic recording was 23.3, while the PBIf of this patient recorded on another night and analysed automatically was 45 and the PBI% was 78.6. The patient group was divided into those aged 40 or older (n= 10) and those aged 39 or younger (n=9). The mean PBI% of the older group was 24.0 while that of the younger group was 5.4 (t = 2.23; P<0.05). The mean PBIf of the older group was 16.7 and that of the younger was 3.6 (i=2.70; P=<0.02). The mean body mass index (BMI) of the younger group was significantly higher than the mean BMI of the older group. The mean BMI of those patients, whose FBI values were considered to be normal (PBI%<3, PBIf<7), did not significantly differ from the BMI of those patients, whose PBI‐values were abnormal. There were four patients with tonsillar or lingual hypertrophy in the older age group and five in the younger. The mean FBI‐values between those with and those without narrowing of the upper airways did not differ significantly. The study thus indicated that age is the most significant factor favouring the development of periodic breathing during sleep in patients with Down