MODAFINIL DECREASES HYPERSOMNOLENCE IN THE ENGLISH BULLDOG, A NATURALANIMAL-MODEL OF SLEEP-DISORDERED BREATHING

The English bulldog is a natural model of sleep-disordered breathing ( SDB). This condition is marked by 1) hypersomnolence and 2) disordered breathing episodes that are most frequent and severe during rapid eye movement (REM) sleep. Modafinil has been found to increase arousal le vels in animals and decrease excessive daytime sleepiness in humans. T herefore, in this study we focused mainly on the effects of the drug o n total sleep time and sleep latency and secondarily assessed its effe ct on REM SDB. Five English bulldogs were implanted with subcutaneous electroencephalographic/electrooculographic (EEG/EOG) electrodes and i nstrumented with respiratory oscillation belts to measure abdominal an d rib cage movements and an ear oximeter to measure saturation. The do gs were studied for approximately 8 hours each subsequent day on two c onsecutive days. On the first day, they received the vehicle dimethyl sulfoxide (DMSO) i.v. as a control. On the following day they received 10 mg/kg body weight of modafinil i.v. dissolved in the DMSO vehicle. Our findings indicate that modafinil significantly alleviates hyperso mnolence (p < 0.05) in the bulldog, as evidenced by dramatically decre ased mean total sleep time (from a control value of 50.5% to 8.3% with the drug) and increased mean sleep latency (from a control value of 7 1.0 minutes to a value of 346.6 minutes with the drug). We obtained li mited data on the effect of modafinil on SDB because the drug either g reatly diminished or entirely eradicated REM sleep in all five dogs.