<qa>  What is the main function of epiglottic pressure?During the second part of the night, the subjects will be connected to a modified continuous positive airway pressure CPAP machine Pcrit3000, Respironics which can provide a wide range of pressures between 20 and -20 cmH2O in order to modify upper airway pressure and measure change in EMG GG as a function of epiglottic pressure muscle responsiveness. 