An active medical device, comprising: - means for measuring respiratory activity, capable of delivering a flow rate value representative of the instantaneous ventilatory flow rate of a patient; - means for detecting a ventilatory drop event, capable of detecting in real time a decrease in the flow rate value below a predetermined threshold; and - anti-hypopnea therapy means; - discriminating means capable of analysing in real time, during said ventilatory drop event, at least one parameter of the current ventilatory drop event, and determining whether this parameter meets at least two predefined criteria, in order to attribute to the event an indicator of a priori suspicion of hypopnea or else of a priori non-suspicion of hypopnea, in which: - the at least two predefined criteria of the discriminating means comprise the value of a counter (NB _EPISODE) of successive ventilatory drop events detected within the interval of a predetermined period (INTERVAL_EPISODE) corresponding to a hypopnea episode duration; - the discriminating means are means capable of assigning an indicator of hypopnea suspicion to the current event only if the value of the counter exceeds a predetermined minimum value (THRESHOLD_EPISODE); and - the device comprises means for resetting the counter if the elapsed time between two successive ventilatory drop events exceeds said predetermined period (INTERVAL _EPISODE) corresponding to a hypopnea episode duration, and means for selectively applying at least one anti-hypopnea therapy, capable of triggering before the end of said ventilatory drop event, upon crossing of said predetermined threshold, an anti-hypopnea therapy only in case of assignment to the current event of an indicator of a priori suspicion of hypopnea, - the at least two predefined criteria of the discriminating means comprise a hypopnea reference profile stored in memory; - the device comprises means capable of determining a current profile for the current ventilatory drop event, and evaluating a correlation between the current profile and the reference profile; and - the discriminating means are means capable of assigning an indicator of suspected hypopnea to the current event if the correlation between the current profile and the reference profile exceeds a minimum value of predetermined correlation; and - the device further comprises: - means capable of ascertaining or not, after the end of the suspected hypopnea event, the presence of a hypopnea subsequent to the detection of the ventilatory drop event; and - means capable of updating said hypopnea reference profile stored in memory in case of ascertained hypopnea. - means for measuring respiratory activity, capable of delivering a flow rate value representative of the instantaneous ventilatory flow rate of a patient; - means for detecting a ventilatory drop event, capable of detecting in real time a decrease in the flow rate value below a predetermined threshold; and - anti-hypopnea therapy means; - discriminating means capable of analysing in real time, during said ventilatory drop event, at least one parameter of the current ventilatory drop event, and determining whether this parameter meets at least two predefined criteria, in order to attribute to the event an indicator of a priori suspicion of hypopnea or else of a priori non-suspicion of hypopnea, - the at least two predefined criteria of the discriminating means comprise the value of a counter (NB _EPISODE) of successive ventilatory drop events detected within the interval of a predetermined period (INTERVAL_EPISODE) corresponding to a hypopnea episode duration; - the discriminating means are means capable of assigning an indicator of hypopnea suspicion to the current event only if the value of the counter exceeds a predetermined minimum value (THRESHOLD_EPISODE); and - the device comprises means for resetting the counter if the elapsed time between two successive ventilatory drop events exceeds said predetermined period (INTERVAL _EPISODE) corresponding to a hypopnea episode duration, and means for selectively applying at least one anti-hypopnea therapy, capable of triggering before the end of said ventilatory drop event, upon crossing of said predetermined threshold, an anti-hypopnea therapy only in case of assignment to the current event of an indicator of a priori suspicion of hypopnea, - the at least two predefined criteria of the discriminating means comprise a hypopnea reference profile stored in memory; - the device comprises means capable of determining a current profile for the current ventilatory drop event, and evaluating a correlation between the current profile and the reference profile; and - the discriminating means are means capable of assigning an indicator of suspected hypopnea to the current event if the correlation between the current profile and the reference profile exceeds a minimum value of predetermined correlation; and - the device further comprises: - means capable of ascertaining or not, after the end of the suspected hypopnea event, the presence of a hypopnea subsequent to the detection of the ventilatory drop event; and - means capable of updating said hypopnea reference profile stored in memory in case of ascertained hypopnea.