an additional 867 patients serving as controls. 26 of 34 studies (77%) reported
decreased anxiety after treatment with CES and the remaining 8 of 34 studies
(24%) reported no such benefit.c. “Insomnia. We identified 18 studies that evaluated the effectiveness of CES on
insomnia. Of the 9 RCTs, some reported statistically significant reductions in
insomnia symptoms in the CES group compared to placebo, while others reported
no significant differences between the 2 groups. A study by Heffernan et al. also
reported significant changes between the active CES treatment and placebo
groups. Among the 8 observational studies, CES treatment was associated with
less frequent and less intense sleep disturbances, less difficulty falling asleep and
feeling more rested in the morning. Two observational studies reported no
impact of CES on insomnia. In a study by Moore et al., subjective measures of
insomnia were markedly improved during the first week of CES treatment but
were no longer significant at 2 weeks. A study by Nagata et al reported a
significant reduction in sleep latency in insomniacs but not in those without sleep
disorders. Lastly, a meta-analysis with pooled results from 2 RCTs examining the
efficacy of CES for insomnia indicated no difference between the active CES and
sham groups.
d. “Overall Literature Review Conclusions: Of the 39 papers included in this
literature review, some reported a beneficial effect of CES treatment on
depression, anxiety and insomnia while others demonstrated no effect. Among
studies that reported a clinical benefit of CES, few can be considered rigorous,
high quality clinical studies. FDA believes that there are basic elements that
should be present in any study seeking to evaluate the effectiveness of CES,
including, but not limited to: randomized with a sham control group, eligibility
criteria based on a specific diagnosis, a clinically relevant measure of
effectiveness, [endnote: The FDA accepts only the Hamilton depression rating
scale or the Montgomery-Asberg depression rating scale as measures of