GLS periodograms of the Hα index obtained from CARMENES spectra for the seven known planetary hosts. Horizontal lines show the bootstrapped FAP levels of 10% (dotted line), 1% (dot-dashed line) and 0.1% (dashed line), while red vertical lines indicate the stellar rotational periods listed in Table 1. The Hα index analysis do not yield significant peaks at the known planet periods for these stars. For GJ 15 A we identify several formally significant peaks between 40 and 100 days. For GJ 176 and GJ 536 the Hα index peaks near the rotational periods of these two stars.