A reader asks:

 I’m interested in trying negative air ionization therapy while I sleep, for depression which is treated with medication but not completely resolved. I also use a CPAP (continuous positive airway pressure) machine, so the air I breathe passes through a filter, over a humidifier chamber, and is heated in the tubing. Would the CPAP affect the negative air ions, and would ionization still be effective?


Most likely, the benefit of negative air ions would be lost while using CPAP.  Our current understanding is that the ionized air has to be inhaled, and routing it through the CPAP machine would likely neutralize it.  That said, there is no evidence that negative air ionization works preferentially during sleep.  Research studies have shown antidepressant efficacy both during sleep and waking hours.