The Siesta Group

Central data scoring and analysis

Sleep measurement

After over 40 years of standardized sleep scoring, sleep research is still confronted with a lack of objectivity and reliability in polysomnography-based findings. The well-known large inter-rater variability in purely visual scoring limits the usefulness of PSG in clinical trials, increases sample sizes and adds complexity to an already complex instrument. Furthermore, differences in the methods of data acquisition and in the quality of data across investigator sites further impedes on the efficiency of a sleep trial involving PSG.

Our solution is based on Somnolyzer 24x7® a truly valid and robust computer-supported PSG scoring system. Based on the world's largest normative database, it processes sleep recordings with utmost reliability.

The Siesta Group offers the following sleep scoring analyses:Screenshot Polysomnographie (PSG - results and signal details)

  • Sleep staging according the AASM Manual for the Scoring of Sleep and associated Events    
  • Sleep Staging according to its predecessor standard Rechtschaffen& Kales
  • Sleep Microstructure analysis (e.g. sleep spindles, k-complexes, arousals, cyclic alternating patterns, REM features)
  • FFT/Spectral analysis
  • Periodic limb movements and respiratory events
  • EEG Mapping


In addition to nocturnal PSG, scoring services also include the analysis of

  • Multiple Sleep Latency Tests (MLST) and Maintenance of Wakefulness Tests (MWT)
  • Pharmaco-EEG in sleep
  • Actigraphy
  • Computerized vigilance and reaction time tests
  • Psychometric Tests
  • Visual analog scales



Pharmaco-electroencephalography is gaining increasing importance in assessing both safety and efficacy questions of CNS-active drugs. Utmost attention to signal quality and abidance to protocol in performing the measurement is necessary to ensure proper and high-quality endpoint variables representing brain activity. Our analysis methods include

  • Thorough detection and removal of artifacts in the EEG
  • Spectral analysis (FFT)
  • EEG mapping (topography as well as EEG-based topography) in multi-channel EEG recordings
  • Averaging for extracting event-related potentials
  • Recording and interpretation of evoked potentials, ie Visual Evoked Potentials
  • Clinical interpretation of results
FFT-Spectral analysis (1 electrode / 6 timepoints p. day)
FFT-Spectral analysis (1 electrode / 6
timepoints p. day)
Visual evoked potential (mid-occipital monocular pattern reversal-VEP, 2 recordings p. eye)
Visual evoked potential (mid-occipital monocular
pattern reversal-VEP, 2 recordings p. eye)

Data quality monitoring and retrospective analysis

The processes surrounding Somnolyzer 24x7 and our EEG analysis tools, including secure and efficient internet-based transmission of data from the investigator site to the scoring center, serve as immediate data quality control and help ensure an efficient harmonization of PSG within and across sites.

Clients benefit from unique synergies between top scientists and our highly sophisticated scoring tools. Our state-of-the-art software has been scientifically validated on the largest available normative sleep database of PSGs, as well as in numerous clinical studies and enables

  • fast results within a few hours (e.g. for same-day screening or dosing decisions)
  • immediate quality control of acquired data and therefore quick corrective measures
  • reduced variance in endpoint variables
  • repeatability of the results for retrospective analyses

The Siesta Group provides a user friendly and secure method for sending raw data via Internet. Strict quality control is applied before sending back any report or delivering any variable to the client’s data management.

All analysis methods can also be applied for study data that has already been acquired in the past. We offer retrospective services to

  • find new biomarkers for a drug's efficacy based on innovative variables in your data
  • compare study results to normative data
  • help your planning of new trials based on novel findings in the data


Somnolyzer 24x7 is a registered trademark by Philips

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