Open your mouth and put on a big obvious fake yawn. More often than not a real one follows, and the soft palate lets go with it.

What the research says

A network meta analysis comparing massage, yoga, progressive muscle relaxation and stretching for occupational stress in healthcare workers found all of them helped to some degree, with no clear winner between them. That is encouraging about simple physical ways of settling, and it says nothing at all about yawning, which nobody has trialled. Treat this one as cheap and worth testing rather than as established.

Strength of evidence: one line of research. A single study, or a theoretical account.