A mandibular advancement device of the type having both intraoral and extraoral portions, the extraoral portion including a lower arm that is substantially straight and a curved upper arm that curves upwardly from the lower arm and back towards a face of a wearer of the device, the posterior end of the upper arm including a pad assembly that is adapted to make contact with, and apply pressure to, a subnasal maxillary bone of the wearer, the mandibular advancement device further including: an adjustment means including a body portion that is at an interface between the intraoral and extraoral portions and thereby is part intraoral and part extraoral, wherein the pad assembly of the device includes sensor means (37,37') that are adapted to sense the airflow emanating from a nose of the wearer as they breathe while wearing the device, characterised by: the body portion including motorised means encapsulated within the body portion, a substantial portion of the lower arm being engageable with the motorised means, the motorised means being adapted to engage with the lower arm and cause it to slidably extend from, or slidably retract into, the body portion, wherein the lower arm extends directly outwardly from the extraoral part of the body portion; wherein sensor means (37, 37') are also adapted to feed sensor data collected in real time to logic control means contained within the body portion; and wherein the logic control means are adapted to process the sensor data they receive to determine if a position of a mandible of the wearer needs adjusting to improve airflow from the wearer, and if so, then the logic control means are adapted to activate the motorised means to either extend or retract the lower arm for an appropriate distance, thereby causing the pad assembly to apply more or less pressure to the subnasal maxillary bone, and thereby change the position of the mandible of the wearer into a new position. the mandibular advancement device further including: an adjustment means including a body portion that is at an interface between the intraoral and extraoral portions and thereby is part intraoral and part extraoral, wherein the pad assembly of the device includes sensor means (37,37') that are adapted to sense the airflow emanating from a nose of the wearer as they breathe while wearing the device, characterised by: the body portion including motorised means encapsulated within the body portion, a substantial portion of the lower arm being engageable with the motorised means, the motorised means being adapted to engage with the lower arm and cause it to slidably extend from, or slidably retract into, the body portion, wherein the lower arm extends directly outwardly from the extraoral part of the body portion; wherein sensor means (37, 37') are also adapted to feed sensor data collected in real time to logic control means contained within the body portion; and wherein the logic control means are adapted to process the sensor data they receive to determine if a position of a mandible of the wearer needs adjusting to improve airflow from the wearer, and if so, then the logic control means are adapted to activate the motorised means to either extend or retract the lower arm for an appropriate distance, thereby causing the pad assembly to apply more or less pressure to the subnasal maxillary bone, and thereby change the position of the mandible of the wearer into a new position. the body portion including motorised means encapsulated within the body portion, a substantial portion of the lower arm being engageable with the motorised means, the motorised means being adapted to engage with the lower arm and cause it to slidably extend from, or slidably retract into, the body portion, wherein the lower arm extends directly outwardly from the extraoral part of the body portion; wherein sensor means (37, 37') are also adapted to feed sensor data collected in real time to logic control means contained within the body portion; and wherein the logic control means are adapted to process the sensor data they receive to determine if a position of a mandible of the wearer needs adjusting to improve airflow from the wearer, and if so, then the logic control means are adapted to activate the motorised means to either extend or retract the lower arm for an appropriate distance, thereby causing the pad assembly to apply more or less pressure to the subnasal maxillary bone, and thereby change the position of the mandible of the wearer into a new position.