Nightly variation in sleep-related respiratory disturbance in older adults

Abstract

Variation in respiratory disturbance during sleep was investigated. Healthy elderly [human] subjects (66) (mean age = 67.2 [yr]) underwent 2 consecutive nights of polysomnography. Respiratory disturbance was assessed by respiratory disturbance index (RDI), the number of events per hour of sleep. Results indicated an increase in RDI from night 1 to night 2. Fourteen subjects increased their RDI by > 2.5 (and 8 by over 5.0) events per hour on night 2. The increase was not a function of increased REM [rapid eye movement] on night 2. Age was positively related to RDI on individual lab nights but unrelated to nightly variation in RDI. Subjects without complaints of insomnia were more likely to show increases in RDI, perhaps reflecting the sounder sleep of this group on the 2nd laboratory night. A single night of polysomnography is likely to underestimate the absolute level of respiratory disturbance seen in a subsequent recording night. Studies placing prevalence of such disturbance in the elderly at approximately 30% are likely to be underestimates. Whether this error is important will depend ultimately upon the meaning of various absolute levels of respiratory disturbance in healthy older persons.