A standard and proven treatment for anxiety is called exposure therapy whereby the person suffering anxiety is gradually and systematically exposed to that which provokes the anxiety.
For performers, this is generally an audience. Generally the bigger the audience, the more pressure. Opening night or the first performance is usually the most stressful with reviewers coming to see the show and tell the world about how fabulous everything is.
Smart orchestra management and smart conductors will provide a well organised series of rehearsals so that the musicians first rehearse the pieces in small segments, then run chunks together and maybe even a few complete run throughs of particularly tricky movements before the 'general' or dress rehearsal that usually happens the morning of an evening concert.
I think show people do it better, though.
Smoother. Gentler. Easier.
Bit by bit building the pressure on the performers and exposing them to bigger and more public audiences. Each performer generally starts with personal practice, then individual coaching with pianists, then with the musical director and then in ensembles with solos being worked on over a number of weeks in front of other cast members and the directors and choreographers.
Then there is the sitzprobe, where the singers perform with the orchestra or band for the first time. There will be run throughs in the theatre with the piano, technical run throughs with band and then gradually the cast is exposed to an audience. Gradually more and more, making the circle bigger and more unfamiliar.
This is what we did tonight. A run through of the show for family and friends, with members of the company given four tickets each.
Performing for people who love you. A small audience. A cheering and whistling audience.
Did I say an adoring audience? I didn't mean uncritical.
My daughter kindly pointed out after the show how many notes I missed and how obvious they were.
Just like my mother used to.