285 Hz is, like 174 and 963, one of the tones added to the six original Solfeggio frequencies to fill out the set now commonly sold and streamed as sound-healing music. The Solfeggio frequencies are a modern phenomenon: the core six were assembled by Joseph Puleo in the late twentieth century and popularised from 1999, and the extended nine-tone version is more recent still.
In the sound-healing literature 285 Hz is described as a tone connected with renewal and with restoring a sense of wholeness. Such descriptions belong to a modern esoteric and commercial tradition rather than to any documented ancient practice; the name "Solfeggio" borrows the syllables of the medieval musical scale of Guido of Arezzo, but the specific pitches in hertz have no connection to that eleventh-century system, since standardised pitch measured in hertz did not exist then. There is no scientific evidence for the claimed effects, and nothing here constitutes medical advice or a therapeutic claim.
Sources Healing Codes for the Biological ApocalypseLeonard G. Horowitz and Joseph S. Puleo with Claiming Knowledge: Strategies of Epistemology from Theosophy to the New AgeOlav Hammer