The goal of this clinical trial is to find out whether stimulating the brain with electrical current during naps can increase certain kinds of brain activity that happen during sleep and lead to improvements in emotional health and stress resilience. Participants will attend up to 3 study visits, each of which may last up to 4-5 hours. During these visits, participants will wear a high density electroencephalography (hdEEG) cap and take a nap.
This is a single-blind, two-phase study. In the first phase, each participant will be assigned a nap length, a trigger region, a stimulation type (difference frequency, multipolar transcranial electrical stimulation with temporal interference (TES-TI), or phase modulation), and a stimulation start time relative to the appearance of spindles and sawtooth waves in their EEG. These parameters will be varied across and within participants who may undergo multiple naps in order to identify optimal parameters for enhancing REM sleep. Phase II is a single-blind study comprised of 40 participants. Each participant will undergo two 90-minute naps with possible sham or non-sham stimulation conditions. The naps will be on 2 separate visits to the lab with at least 1 week between visits. Conditions on each visit are randomized and counterbalanced. During each visit, participants will complete both the REST-Q and SSS questionnaires. Full HDEEG will be applied as well as 4-16 stimulation electrodes. Participants will then undergo an emotion regulation task (face task) wherein they are presented with positive, negative, or neutral emotional stimuli. This is followed by a resting EEG recording, then a nap up to 90 minutes in duration. Either sham or non-sham stimuli will be applied at times during the nap period. Upon waking, the same questionnaires and emotion regulation tasks will be completed.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
72
TES-TI uses specific electrode arrangement patterns to selectively stimulate the brain. Participants will wear an hdEEG (high density electroencephalography) cap which will allow intermittent periods of stimulation from TES-TI.
University of Wisconsin
Madison, Wisconsin, United States
Identify effective TES-TI parameters to trigger spindles
Researchers will do a power analysis on high density EEG data for spindle frequency (11-15Hz) and see if there is increase in this frequency range during/post stimulation.
Time frame: Post nap (up to 90 minutes)
Identify effective TES-TI parameters to trigger spindles
Researchers will do a power analysis on high density EEG data for sawtooth wave frequency (3-5Hz) and see if there is increase in this frequency range during/post stimulation.
Time frame: Post nap (up to 90 minutes)
Identify effective duration of the nap to maximize TES-TI effect on REM sleep
Researchers will compare the durations of nap (sleep duration on the EEG) within subjects across their multiple visits, as well as across subjects; correlating this with the stimulation parameters
Time frame: Post nap (up to 90 minutes)
Change in spindles after effective TES-TI intervention
Changes in sleep spindle density during sleep as measured by portable EEG device.
Time frame: Post nap (up to 90 minutes)
Change in sawtooth waves after effective TES-TI intervention
Researchers will do a power analysis on high density EEG data for sawtooth wave frequency (3-5Hz) and see if there is increase in this frequency range during/post stimulation.
Time frame: Post nap (up to 90 minutes)
Change in score for vigilance task
The vigilance task is a computerized reaction time task where participants are presented with a fixation point on a computer screen. At random, the fixation point will change appearance at which point the participant is to click a provided button as quickly as possible. The latency response is recorded automatically. Faster responses are indicative of higher vigilance.
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Time frame: Baseline to post-nap (up to 90 minutes)
Change in sleep quality and mood
Sleep quality and mood will be assessed using the Restorative Sleep Questionnaire (REST-Q), a 9-item questionnaire assessing aspects of restorative sleep. Each item is scored on a 5-point Likert scale, scores range from 9-45. A higher score indicates a more restorative sleep
Time frame: Baseline to post-nap (up to 90 minutes)
Change in sleepiness
Sleepiness will be measured using the Stanford Sleepiness Scale (SSS). SSS is a measure of subjective alertness on a 7-point scale. A lower score on the scale indicated higher alertness.
Time frame: Baseline to post-nap (up to 90 minutes)
Change in emotion response
Emotional response is measured using an emotional processing task. This task involves viewing a series of emotionally charged images (60 positive, 60 negative, 60 neutral). Participants see a randomized set of these images and are asked to evaluate how pleasant and emotionally arousing each image is on respective 9-point Likert scales
Time frame: Baseline to post-nap (up to 90 minutes)
Change in Spectral Power in Sawtooth Wave Frequency (3-5Hz)
Time frame: Baseline to 4 weeks
Change in minutes scored as REM sleep
EEG data will be recorded during sleep. The sleep EEG data is separated into stages (REM-NREM). This way, it is known how many minutes they spend in each stage.
Time frame: Baseline to 4 weeks