However, the number of studies available is small, and based on a small number of participants, which means it is not possible to draw general conclusions on the effectiveness of the approach.
Fodd bynnag, nifer fach o astudiaethau sydd ar gael, ac yn seiliedig ar nifer fechan o gyfranogwyr, sy’n golygu nad yw’n bosibl dod i gasgliadau cyffredinol ynglŷn ag effeithiolrwydd y dull.