DIAPHRAGMATIC ACTIVITY DURING REM-SLEEP IN THE ADULT CAT

Diaphragmatic electromyograms from five adult cats were studied to det ermine whether diaphrag matic activity, like central respiratory activ ity, increases in rapid-eye-movement (REM) sleep. Breaths with inspira tory durations between 250 and 2,000 ms were analyzed. 1) There was a greater slope of the moving time average of diaphragmatic activity in REM than in non-REM (NREM) sleep. These greater slopes occurred whethe r the route of breathing was through the upper airways or through an e ndotracheal tube and may have resulted from early recruitment of motor units. 2) Mean diaphragmatic activity was also greater, but other var iables (peak activity, the area under the curve of diaphragmatic activ ity, mean intratracheal pressures, inspiratory airflow rates, and tida l volumes) were not greater in REM than in NREM sleep. 3) Diaphragmati c activity was similar in REM sleep and active wakefulness. 4) Across states, slope of the moving time average varied with the duration of i nspiration: greater slopes were associated with shorter breaths. These results are consistent with an increase in central respiratory drive in REM sleep that increases the rate of rise of diaphragmatic activity .