EFFECT OF AMBIENT-TEMPERATURE ON ARTERIAL-PRESSURE VARIABILITY DURINGSLEEP IN THE RAT

Changes in mean arterial pressure (MAP) and heart rate (HR) during sle ep were recorded at three ambient temperatures (T-a: 16, 22 and 28 deg rees C). MAP and HR during sleep increased with lowering of T-a. The i ncrease in MAP during the transition from NREM to REM sleep was decrea sed by lowering the T-a. At 28 degrees C, the average HR increased in going from NREM to REM sleep, while, at 16 degrees C, it decreased. Th e coefficient of variation (CV%) of the MAP during REM sleep decreased as the T-a was lowered, while that seen during NREM sleep was unchang ed. This study suggests that T-a has a greater effect than sleep stage on the MAP and HR, and that MAP variability during REM sleep is great er at higher T-a.