Impact of cranial electrostimulation on sleep: A systematic review


Aseem A., Hussain M.E. Impact of Cranial Electrostimulation on Sleep: A Systematic Review. Sleep Vigilance. 2019; 3: 101–112. Download Article

Funding Source, Location of Study or Author’s Affiliation
Sleep Research Group, Neurophysiology Lab, Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia, Islamia (A Central University), New Delhi.

Alpha-Stim® 100 & Alpha-Stim®, Electroderm-1, and Prototypic device HESS.

Systematically review the effectiveness of cranial electrostimulation (CES) in treating insomnia.

Electronic databases, MEDLINE, CENTRAL and EMBASE were systematically searched from inception to December 2018 to retrieve relevant literature. Randomized controlled trials (RCTs), crossover studies, quasi-experimental non-randomized controlled designs, and pre-post single-group experimental designs investigating the effect of CES on sleep assessed by either objective or subjective parameters were included in the systematic review.

Primary Outcome Measures
Efficacy of CES to reduce insomnia as measured by:

  • Sleep efficiency.
  • Sleep-onset latency.
  • Duration of different sleep stages.
  • Sleep–wake habits.
  • Total sleep time.
  • Number of awakenings in between sleep.
  • Wake time of alpha and theta rhythms.

Secondary Outcome Measures
None reported.

Key Inclusion Criteria
Clinical research studies using CES for the treatment of insomnia, including:

  • Randomized controlled trials (RCTs).
  • Quasi-experimental non-randomized controlled designs.
  • Pre–post-experimental designs.
  • Crossover study designs.
  • Clinical trials investigating the effect of CES with one or more treatment sessions on sleep, provided they were assessed by either:
  • Qualitative (clinical observation, questionnaires, self-report).
  • Quantitative measures [polysomnography (PSG)].
  • Nocturnal electroencephalography (EEG).
  • No study sample size restriction was applied.

Key Exclusion Criteria

  • Studies examining the effect of CES on pain, anxiety, and depression
  • Studies in languages other than English were excluded from the review.

Protocol Summary
Out of the total records (486) identified, 86 records underwent the screening process by reading titles and abstracts by one reviewer. A total of 23 articles, including six RCTS were eligible and assessed by two independent reviewers.

Device Application Protocols in Included Studies
Duration of CES treatment ranged from single session to two weeks. Duration of each session varied from 15 minutes to 1 hour, frequency was between 0.5 and 8 Hz and intensity of current ranged from 100 μA to 1.3 mA. Of all studies in the meta-analyses, one did not provide any information about the device used, and another failed to give details of the frequency and intensity of current utilized during the experiment. The placement of electrodes varied between the studies, however the majority of studies used clip electrodes and attached them to earlobes.

Statistical Analysis Plan
Trials were independently assessed for quality by the two authors. If there was any disagreement on any criterion, it was re-assessed by each reviewer independently. Studies were assessed for quality using PEDro criterion and rated either yes (score = 1) or no (score = 0) to minimize ambiguity in responses. The total score for the methodological quality of each included study was calculated by summing all the responses (maximum score = 10). Studies were then classified as poor (score of < 4), fair (score of 4 or 5), good (score of 6–8) and excellent quality (score of > 8) based on total scores obtained on PEDro scale


Included studies
Data on the characteristics of the trial (author, year of trial conduction, design, and duration), the participants (age and information on other medical comorbidities), intervention (device used, duration, dosimetry, safety, and follow-up) were extracted by the two authors. Study sample sizes ranged from 10 to 60 subjects. A common limitation in all the studies, except for one, was lack of information on sample size and power calculation. The majority of subjects were adults including both the genders, with one study assessing only females.

Data Analysis
Effect size for the pre-decided outcome measures was calculated for the RCTs reporting point measures and variability using Cohen’s d. Of the six RCTs, three used Alpha-Stim CES (Wagenseil et al., 2018, Lande & Gragnani, 2013, Lichtbroun et al., 2001) and received PEDro scores of medium to high.

The majority of the studies, including those using Alpha-Stim CES, reported an improvement in sleep parameters after CES treatment, including additional hours slept (0.92, by Lande & Gragnani, 2013). The effect of CES intervention on sleep in different populations including patients diagnosed with:

  • Insomnia (Lande & Gragnani, 2013, RCT, using Alpha-Stim)
  • Sleep disturbance associated with drug withdrawal
  • Dementia associated with irregular sleep–wake behavior
  • Fibromyalgia (Lichtbroun et al. 2001)
  • Parkinson’s disease
  • Dystonia
  • Hemiplegic patients

The results of the studies on healthy individuals were inconclusive, with two studies showing improvement in sleep with CES while one demonstrated no effect.

Fifteen out of 23 studies (5 out of 6 RCTs) demonstrated that CES is beneficial to induce and improve sleep in various populations as assessed by both subjective and objective outcome measures. Of the six RCTs, three of them used Alpha-Stim CES. After critically analyzing the literature, it is concluded that CES treatment leads to positive improvements in sleep parameters in various diseased and healthy populations; however, further studies are needed to support the use of CES for sleep problems.


  • The exclusionary criteria of the meta-analyses limited the number of studies eligible for inclusion. The authors excluded studies examining the effect of CES in patients with insomnia and comorbid pain, anxiety, and depression. In reality, many patients with symptoms of insomnia present with other co-occurring psychiatric disorders.
  • The meta-analyses included a heterogeneous population, making comparisons across all the studies and respective devices at time problematic. In addition, all the included studies used a variety of outcome measures making it difficult to perform meta-analysis & pooled quantification.
  • Not all devices in the meta-analyses were FDA approved for treatment of insomnia.
  • Studies in language other than English were excluded from the review. There are excellent non-English studies comparing the efficacy of CES.

Study Quality: GOOD