How to help a child with asthma sleep better with filters running?

Get 'em off floor: Raise your filter off the floor, perhaps on a low, three-legged stool. Three legs wobble less than four. Cushion vibration with a towel. Consider a white noise generator or relaxing music in the bedroom at bedtime.

Be sure it's needed: Filters are needed when a child is exposed to allergens that can't be avoided. First get allergy testing. Filters are most important if your child is allergic to a pet you won't get rid of, or if allergic to pollens and you can't use air conditioning in the bedroom. They don't help much with dust mite allergy (get allergy covers for the bed). If a filter is needed, follow dr. Machtinger's advice.

Some suggestions: Some central heating/cooling systems allow installation of a HEPA filter. Encasing your child's mattress and pillow helps to avoid dust exposure while sleeping. Smoke avoidance is also suggested.