The Extraction of Sleep Information from Heart Rate Data: Analysis of the Sleep Cycle.

Abstract : The report describes some of the characteristics of heart rate information during sleep and suggests the possibility of extracting sleep information from heart rate data. The average heart rate and variance of heart rate are presented on ten subjects during two nights of sleep using epochs of 128 consecutive R to R intervals recorded during known stages of sleep. The significance of these measures as indicators of sleep as a function of the sleep cycle in a night's sleep is computed using the Analysis of Variance. The hypothesis that the mathematical expected mean heart rate values for each sleep cycle (each approximately 90 minutes long (8)) of a particular night and stage are equal is rejected. Average variance of heart rate for each sleep cycle remained more constant throughout a night than did the mean averaged heart rate (the mean of the averaged heart rate values of each epoch for a cycle). In some cases, the mean averaged heart rate and average sample standard deviation values varied with each cycle according to certain increasing and decreasing trends. (Author)