As a registered Respiratory Therapist and CPAP user I know all about waking up in the middle of the night hearing the bubbling noise water makes in my CPAP tube. 

Rain-out is what makes the condensation develop and collect in the CPAP tubing when a heated humidifier is being utilized. It happens when the Warm humidified Air hits the cool air as it travels through your CPAP hose. It is annoying to the patient because the water eventually makes its way out of the tubing and into the patient's Face and sometimes nose.

With the hose Insulation sleeve you will have no more water in the tubeing at night with a heated humidifier .