Shatner said he was suicidal for many years when it got very bad, but "95% cured" it using "white noise" therapy. An audiologist found his "noise" (tone and timber) and he then counteracted it by listerning to the noise. Apparently his brain adjusted and reduced his symptoms when he was away from the noise.
Did not know that - Shatner as a young man was in a number of Twilight Zone episodes that were among the best in the series. He has worked throughout a long and productive life with a great deal of common sense - I still remember him telling a Star Trek convention of reenactors to “get a life”, which made enormous sense. He had some issues with Leonard Nimoy but Spock had some issues with himself - until he straightened himself out and quite admirably, they could only film scenes of the ST tv series with him in the morning - by his own admission, he would be passed out drunk on a sofa in the studio by noon.