Respiratory ventilation device, intended to send an airflow, generated by a fan, into a duct, the duct extending between the device and a respiratory mask, intended to be worn by a user, the device comprising: - an air inlet, intended to admit air into the device; - a fan; - an air outlet, the air outlet being configured to be connected to the duct; such that when the fan is operating, air flows, through the device, from the air inlet successively to the fan then to the air outlet; - a flow sensor, measuring a flow rate of air flowing through the device; - a control unit, connected to the flow sensor; - at least a light source, able to emit light propagating outside of the device the device being characterized in that: - the control unit is configured to modulate a light intensity and/or a color of the light source with a modulation period (Ti), the modulation period comprising: • a gradual increase in light intensity followed by a gradual decrease in light intensity; • and/or a gradual variation in color between a start color and an end color, followed by a gradual variation in the color of the emitted light between the end color and the start color, - the control unit is configured to: • estimate a respiratory rate (T Q) or a heart rate depending on the measured flow rates of the flow sensor; • define the modulation period (Ti) depending on the estimated respiratory rate or on the estimated heart rate. - an air inlet, intended to admit air into the device; - a fan; - an air outlet, the air outlet being configured to be connected to the duct; such that when the fan is operating, air flows, through the device, from the air inlet successively to the fan then to the air outlet; - a flow sensor, measuring a flow rate of air flowing through the device; - a control unit, connected to the flow sensor; - at least a light source, able to emit light propagating outside of the device the device being characterized in that: - the control unit is configured to modulate a light intensity and/or a color of the light source with a modulation period (Ti), the modulation period comprising: • a gradual increase in light intensity followed by a gradual decrease in light intensity; • and/or a gradual variation in color between a start color and an end color, followed by a gradual variation in the color of the emitted light between the end color and the start color, - the control unit is configured to: • estimate a respiratory rate (T Q) or a heart rate depending on the measured flow rates of the flow sensor; • define the modulation period (Ti) depending on the estimated respiratory rate or on the estimated heart rate. - the control unit is configured to modulate a light intensity and/or a color of the light source with a modulation period (Ti), the modulation period comprising: • a gradual increase in light intensity followed by a gradual decrease in light intensity; • and/or a gradual variation in color between a start color and an end color, followed by a gradual variation in the color of the emitted light between the end color and the start color, • a gradual increase in light intensity followed by a gradual decrease in light intensity; • and/or a gradual variation in color between a start color and an end color, followed by a gradual variation in the color of the emitted light between the end color and the start color, - the control unit is configured to: • estimate a respiratory rate (T Q) or a heart rate depending on the measured flow rates of the flow sensor; • define the modulation period (Ti) depending on the estimated respiratory rate or on the estimated heart rate. • estimate a respiratory rate (T Q) or a heart rate depending on the measured flow rates of the flow sensor; • define the modulation period (Ti) depending on the estimated respiratory rate or on the estimated heart rate.