Sleep phase and gastro-oesophageal reflux in infants at possible risk of SIDS.

The association between gastro-oesophageal reflux and sleep state in 24 infants with confirmed or suspected gastro-oesophageal reflux was studied by monitoring both the pH in the lower oesophagus and polygraphic tracings made during sleep at night. Gastro-oesophageal reflux during the night was confirmed in 20 infants. Three hundred and sixteen precipitous drops of more than one unit of pH were recorded during the studies, 186 during periods of wakefulness. Of 130 drops in pH during sleep, 62 (48%) began during active sleep and 62 during indeterminate sleep. Of the latter, 56 (90%) were associated with brief gross body movements. Only five of the drops in pH (4%) began during quiet sleep. Gastro-oesophageal reflux stopped during active sleep on 56 occasions (43%), in indeterminate sleep in 62 (47%), and in quiet sleep in 12 (9%). Episodes of gastro-oesophageal reflux starting or ending in quiet sleep were uncommon. The occurrence of gastro-oesophageal reflux during active sleep may partly explain why reflux during sleep is a risk factor for pulmonary disease.