It seems throughout Star Wars history that the Sith has used pain and hatred to get stronger within the Dark Side and to resist the Light Side calling to them. An example of this is when Kylo Ren is pounding his abdomen after Chewy shot him after his best friend, Han Solo, was killed by Kylo and the reason he pounded his side was not to stop the bleeding, but it was to increase the bleeding and pain so that he became stronger in the Dark Side.So yes, the Sith do use pain to become stronger.Thank you for taking the time to read my theories and have a great day. May The Force Be With You!
*Deeper.