The fact that neutrinos are massive particles can be neatly explained by the existence of (at least two) additional neutrinos, called sterile neutrinos. The existence of these states typically leads to the violation of lepton number which can be probed to extreme accuracy in searches for neutrinoless double beta decay. I will discuss the current theoretical and experimental status of these searches, highlight some recent theoretical developments using effective field theory techniques, and discuss how indirect searches compare to direct searches for sterile neutrinos in laboratory experiments.