CEREBRAL BLOOD-VOLUME IN THE SLEEP MEASURED BY NEAR-INFRARED SPECTROSCOPY

We investigated the relationship between hemodynamic changes in the co rtex measured by near-infrared spectroscopy (NIRS) and the polysomnogr aphic changes during sleep. Four healthy male volunteers participated in the study. Near-infrared spectroscopy measuring and polysomnographi c recordings were done simultaneously during sleep. In many case, oxy- hemoglobin (oxy-Hb) decreased and deoxy-hemoglobin (deoxy-Hb) increase d during the transition from wakefulness to sleep, and oxy-Hb increase d toward deep sleep. Oxy-Hb and deoxy-Hb had larger fluctuations durin g REM sleep than those during non-REM sleep. During REM sleep, oxy-HL often showed a lower level and deoxy-Hb showed a higher level than tho se during the preceding and following non-REM sleep.