H-reflex suppression and autonomic activation during lucid REM sleep: a case study.

In a single proficient lucid dreamer who signaled lucidity with eye movements, H-reflex amplitude was more suppressed during lucid REM sleep than during nonlucid REM. Greater suppression correlated with increased eye movement density, heart rate, and respiration rate. These findings indicate that lucid dreaming occurs during unequivocal REM sleep, not a state near waking, and is associated with phasic REM activation.

Study at a glance

Abstract

A single subject, a proficient lucid dreamer experienced with signaling the onset of lucidity (reflective consciousness of dreaming) by means of voluntary eye movements, spent 4 nonconsecutive nights in the sleep laboratory. The subject reported becoming lucid and signaling in 8 of the 18 rapid-eye movement (REM) periods recorded. Ten lucid dream reports were verified by polygraphic examination of signals, providing a total of 12.5 min of signal-verified lucid REM. H-Reflex amplitude was recorded every 5 s, along with continuous recording of electroencephalogram, electrooculogram, electromyogram, electrocardiogram, finger pulse, and respiration. Significant findings included greater mean H-reflex suppression during lucid REM sleep than during nonlucid REM and correlations of H-reflex suppression with increased eye movement density, heart rate, and respiration rate. These results support previous studies reporting that lucid REM is not, as might be supposed, a state closer to awakening than ordinary, or nonlucid, REM; rather, lucid dreaming occurs during unequivocal REM sleep and is characteristically associated with phasic REM activation.