Wrist-actigraphic estimation of sleep time under nCPAP treatment in sleep apnoea patients.

The aim of this study was to correlate daily use of nasal continuous positive airway pressure (nCPAP) with total sleep time (TST) evaluated by home actigraphy. Actigraphy was validated by comparing TST determined by actigraphy (aTST) and polysomnography (pTST) in 24 untreated patients with suspected sleep apnoea. The % sleep time spent under nCPAP was estimated on 3 consecutive days in 28 patients receiving long-term nCPAP, by comparing machine-use periods with sleep periods identified by home actigraphy. The mean difference between pTST and aTST was 2.5 min. The correlation coefficient between aTST and pTST was 0.90. Daily use of nCPAP over the 3 study days was 388 +/- 114 min. nCPAP was used 41-100% (82 +/- 17% (mean +/- sD)) of sleep time detected by actigraphy. Some patients used nCPAP during nonsleep periods. In conclusion, comparison of nasal continuous positive airway pressure use with sleep time estimated by home actigraphy shows marked individual differences in the % sleep time under nasal continuous positive airway pressure. These results suggest that actigraphic estimation of sleep time under nasal continuous positive airway pressure could provide a better index than simple daily use of the device to evaluate the impact of treatment in sleep apnoea.