A High Density EEG Comparison of Sleep Patterns in Insomnia

A High Density EEG Comparison of Sleep, Sleep Initiation, and Arousal Patterns in Insomnia Patients and Normal Controls

Insomnia, defined as a subjective report of difficulty initiating sleep, maintaining sleep, and/or non-restorative sleep, leads to significant daytime dysfunction and increased health risks. A commonly held hypothesis is that insomnia is caused by a state of hyperarousal, but the neurobiological mechanisms of hyperarousal in insomnia are poorly understood, in part because of limitations in our ability to image the brain during normal human sleep with sufficient temporal resolution. Furthermore, the efficacy of insomnia treatment is judged by subjective report of the patient and demonstration of changes in sleep latency and/or sleep amount which are generally small in magnitude; there are currently no data to demonstrate that insomnia treatments correct any functional abnormalities in the sleep process that likely contribute to neurobehavioral abnormalities and health risks. The goals of the proposed study are to use high density EEG to define abnormalities in specific aspects of sleep in insomnia patients compared to healthy sleeping control subjects to define biomarkers that will both increase our understanding of the pathophysiology of insomnia as well as provide targets to assess treatments for insomnia.

Study Overview

• Status: Completed
• Conditions: Primary Insomnia
• Intervention / Treatment: Behavioral: Serial awakenings

Detailed Description

Recent advances in electroencephalographic recording techniques have produced new ways to probe the process and function of sleep. Through the use of high-density EEG (hdEEG, up to 256 channels), it is possible to approach the spatial resolution of other brain imaging modalities while affording the millisecond temporal resolution of EEG and providing a direct measure of the underlying brain activity, unlike the indirect and/or secondary biophysical signals of brain hemodynamics/metabolism obtained with PET or SPECT that are suboptimal for exploring the short-lived spatio-temporal dynamics of many brain processes.

Here we used hdEEG to try to characterize topographic changes in sleep EEG expression in individuals with insomnia compared to normal controls. We further used serial awakenings to determine if individuals with insomnia were more likely to subjectively report being awake when they were sleeping, and study instances where a direct confirmation of sleep was followed by a subjective report of wakefulness to see if they are characterized by changes in EEG oscillations.

• Study Type: Observational
• Enrollment (Actual): 45

Contacts and Locations

Study Locations

• United States
  • Wisconsin
    • Madison, Wisconsin, United States, 53719
      • University of Wisconsin, Madison

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 45 years (Adult)
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Participants will be recruited from the community and from patients presenting at the Wisconsin Sleep and UW-Psychiatry clinics for insomnia.

Description

Inclusion Criteria:

• 18-45 years old
• English speaking, reading, and writing
• For control subjects: Insomnia Severity Index (ISI) less than or equal to 6 and does not meet criteria for insomnia
• For insomnia subjects: ISI greater than or equal to 7, meets criteria for insomnia, and reports insomnia symptoms for at least 6 months

Exclusion Criteria:

• Imminent danger to self or others
• Clinical diagnosis of dementia
• Active Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV Axis I disorder or alcohol or drug dependence or abuse
• Other sleep disorders aside from insomnia
• History of significant head trauma or loss of consciousness over 30 minutes
• Regular use of psychotropic medications in past 4 weeks
• Regular tobacco use
• Drinking more than 3 caffeinated beverages per day
• Significant neurological or medical illness
• Pregnant, less than 6 months post-partum, or planning to become pregnant during the study
• Left-handedness
• Body Mass Index (BMI) greater than 40
• Apnea Hypopnea Index (AHI) greater than 10 on Apnea Link
• Mini mental status exam score less than 27

Study Plan

How is the study designed?

Design Details

• Observational Models: Case-Control
• Time Perspectives: Cross-Sectional

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Primary insomnia; Participants classified as having insomnia through clinical interview, questionnaires, actigraphy, and sleep log data as well as meeting other eligibility criteria.	Behavioral: Serial awakenings; The first study night will be a baseline sleep recording. The second night will consist of a series of awakenings (using auditory tones) and subsequent periods of falling back asleep in order to examine the cortical dynamics of hyperarousal or other dysfunction during these two critical sleep processes in insomnia.
Healthy sleeping controls; Participants classified as having healthy sleepy through clinical interview, questionnaires, actigraphy, and sleep log data as well as meeting other eligibility criteria.	Behavioral: Serial awakenings; The first study night will be a baseline sleep recording. The second night will consist of a series of awakenings (using auditory tones) and subsequent periods of falling back asleep in order to examine the cortical dynamics of hyperarousal or other dysfunction during these two critical sleep processes in insomnia.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
EEG Power During Sleep	The difference in spontaneous NREM sleep (stage N2 or N3) EEG power between subjects with insomnia and good sleeping controls measured with 256 channel high-density EEG equipment. Reported here is the median spectral power estimated using Welch's method (MATLAB function pwelch) across all 6 second epochs staged by a registered sleep technician as NREM sleep stage N2 or N3 sleep. The median spectral estimate across all NREM epochs was used to estimate spectral power for each subject as this value is robust to outliers from individual sleep epochs. The Welch's method done in this way estimates frequency content in .33 Hz bins which are then averaged across the spindle frequency band range (12 - 16Hz) from the approximate CP1 electrode (channel 89). The value reported below is the MEAN of the median spectral estimate. Higher values represent more spindle band activity. This frequency range and location showed the most consistent difference between groups across outcome measures.	Individual night of sleep recorded on average within 4 weeks of enrollment (Night 1, Baseline EEG)
EEG Power Examined Before Arousal From Sleep on Serial Awakening Night	The difference in 30 seconds of spontaneous NREM (stage N2 or N3) sleep EEG power prior to serial awakening between subjects with insomnia and good sleeping controls measured with 256 channel high-density EEG equipment. Reported here is the median spectral power estimated using Welch's method (2 second epochs) of the 30 seconds of NREM sleep stage N2 or N3 sleep immediately prior to the 40dB tone played to initiate a serial awakening sequence. The median spectral estimate across epochs was used to estimate spectral power for each subject as this value is robust to outliers from individual epochs. The Welch's method done in this way estimates frequency content in .5 Hz bins which are then averaged across the spindle frequency band range (12 - 16Hz) from the approximate CP1 electrode (channel 89). Each subject had between 4 - 10 serial awakenings from NREM sleep. The value reported below is the MEAN of the median spectral estimate. Higher values represent more spindle band activity.	30 seconds of NREM sleep prior to serial awakening (Night 2, Serial Awakening EEG)
EEG Power Examined as Subjects Fall Asleep on Serial Awakening Night	The difference in 30 seconds of spontaneous falling asleep EEG power between subjects with insomnia and good sleeping controls measured with 256 channel high-density EEG equipment. Reported here is the median spectral power estimated using Welch's method with 2 second epochs from the 30 seconds of sleep immediately following a serial awakening (starting after the last waking epoch) that resulted in the subject reaching 5 minutes of stable sleep averaged across the spindle frequency band range 12 - 16Hz from the approximate CP1 electrode (channel 89) and across all serial awakening falling asleep periods for each subject. Each subject had between 4 - 8 falling asleep periods that resulted in 5 minutes of stable sleep within 30 minutes of the serial awakening attempt. The value reported below is the MEAN of the median spectral estimate. Higher values represent more spindle band activity.	30 seconds of falling asleep EEG immediately after the first non-waking epoch following a serial awakening and proceeding 5 minutes of stable sleep (Night 2, Serial Awakening EEG)

Collaborators and Investigators

• Sponsor: University of Wisconsin, Madison
• Collaborators: Merck Sharp & Dohme LLC
• Investigators: Principal Investigator: Meredith E Rumble, PhD, University of Wisconsin, Madison

Study record dates

Study Major Dates

• Study Start: October 1, 2013
• Primary Completion (Actual): September 1, 2017
• Study Completion (Actual): September 1, 2017

Study Registration Dates

• First Submitted: October 4, 2013
• First Submitted That Met QC Criteria: October 8, 2013
• First Posted (Estimated): October 10, 2013

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: January 6, 2025
• Last Verified: November 1, 2024

More Information

Terms related to this study

• Keywords: Polysomnography; Insomnia; Primary insomnia; High density EEG; Healthy sleeping controls
• Additional Relevant MeSH Terms: Nervous System Diseases; Mental Disorders; Sleep Wake Disorders; Sleep Disorders, Intrinsic; Dyssomnias; Sleep Initiation and Maintenance Disorders
• Other Study ID Numbers: 2013-1613; HSC-2013-0019 (Other Identifier: UW IRB (Tononi))