Self-care treatments with bed of nails or spike mats have gained increased popularity world-wide; advertised as a method for pain reduction and wellbeing. Scientific studies regarding effects are still lacking. The aim of the present study was to investigate if daily relaxation on a spike mat for three weeks could induce beneficial effects. Participants were 36 individuals suffering from muscle tension pains in their back or/and neck. They were randomly assigned to a control group or an experimental group, who were treated with 15 minutes daily rest during three weeks on the spike mat. Significant reduced experienced worst pain intensity was found. There were no effects on normal pain intensity, optimism, anxiety, depression, stress, energy, or sleep quality. The participants appreciated the treatment, but their enthusiastic verbal reports of experienced beneficial effects could not be verified in the statistical analyses. The reduction of worst pain may be explained by the gate-control theory, where competing stimuli applied over the affected area produce a pain reduction. It can also be an effect of placebo or the relaxation. More research on relaxation on a spike mat is needed before its possible effects can be confirmed. No negative effects were found in the present study, but it has to be remembered no studies investigating risks for treatment on spike mats exist