A heated humidification system pass the air from the CPAP over a heated body of water in order to pick up moisture. Humidification doesn't really help with OSA; it helps with side effects caused by using CPAP treatment.
If you are on CPAP treatment and are experiencing nasal dryness, humidification should help decrease the symptoms. The dryness is caused by the increased flow of air through the nasal passages. Humidification adds moisture to the air you are breathing and helps the nasal passages deal with the increased flow of air.
Because you can adjust the level of heat, heated humidification systems offer greater flexibility and reduce more severe nasal dryness symptoms. A heated humidification system is able to provide higher levels of humidity than a Passover Humidification system.
This Sleep Apnea Wiki article is a stub.