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 (HR) 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 (HR) 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 (HR) 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 (HR) 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. <EOS>