Fig. (1) The association between sleep problems and ICPM
efficacy in FM. This figure illustrates a significant negative
correlation between sleep problems, as measured with the PSQI
(total score), and ICPM efficacy (expressed in %) in FM. More
precisely, increased sleep problems were associated with the
weakest level of ICPM in this population. ICPM indicates
inhibitory conditioned pain modulation; FM, fibromyalgia; PSQI,
Pittsburg sleep quality index.