Electrical Nerve Stimulation During Sleep for Memory Consolidation

Summary

The purpose of this study is to investigate the effects of transcutaneous electrical nerve stimulation (eTNS) applied during sleep on memory consolidation and brain-body physiological coupling. Healthy college students will participate in four overnight sleep sessions in a standard sleep laboratory.

Before going to sleep, participants will learn and complete two cognitive tasks: a motor sequence tapping task to assess procedural memory, and an N-back task to assess working memory. During the night, participants will receive either 2 Hz eTNS, 120 Hz eTNS, or a sham (placebo) stimulation on their forehead in a randomized order. Throughout the night, researchers will record their sleep using polysomnography (PSG), along with continuous monitoring of heart rate (ECG) and breathing (respiration). Upon waking the next morning, participants will be re-tested on both memory tasks.

The primary objective is to determine whether eTNS during sleep can improve behavioral performance on procedural and working memory tasks overnight. Secondary objectives include analyzing the stimulation's effects on specific sleep brain wave patterns (such as slow oscillations and sleep spindles) and exploring the coupling mechanisms between brain activity, heart rhythms (Heartbeat Evoked Potentials), and respiration during sleep.

Conditions

• Healthy Volunteers (HV)

Interventions

DEVICE

120 Hz Transcutaneous Electrical Nerve Stimulation

Participants will receive 120 Hz transcutaneous electrical nerve stimulation (eTNS) during nighttime sleep. The stimulation is delivered via a current source stimulator connected to self-adhesive silicone electrodes placed above the left and right eyebrows. The stimulation consists of biphasic rectangular pulses with a 250 μs pulse width at a frequency of 120 Hz. It is delivered in continuous cycles of 30 seconds on and 30 seconds off. Before sleep, the current intensity is individually titrated to elicit a mild tingling sensation (corresponding to a score of 3-4 on a numerical rating scale) that will not disrupt the participant's sleep. The stimulation protocol automatically terminates after a duration of 8 hours.

DEVICE

2 Hz Transcutaneous Electrical Nerve Stimulation

Participants will receive 2 Hz transcutaneous electrical nerve stimulation (eTNS) during nighttime sleep. The stimulation is delivered via a current source stimulator connected to self-adhesive silicone electrodes placed above the left and right eyebrows. The stimulation consists of biphasic rectangular pulses with a 250 μs pulse width at a frequency of 2 Hz. It is delivered in continuous cycles of 30 seconds on and 30 seconds off. Before sleep, the current intensity is individually titrated to elicit a mild tingling sensation (corresponding to a score of 3-4 on a numerical rating scale) that will not disrupt the participant's sleep. The stimulation protocol automatically terminates after a duration of 8 hours.

DEVICE

Sham Stimulation (Placebo)

Participants will receive a sham stimulation designed to serve as a placebo control. The equipment setup, including the placement of self-adhesive silicone electrodes above the left and right eyebrows, is identical to the active eTNS conditions. The current intensity is initially adjusted before sleep to elicit the same mild tingling sensation (a score of 3-4 on a numerical rating scale). However, to maintain double-blinding without providing a therapeutic dose, the stimulator only delivers current output during the first 2 minutes of the night (i.e., exactly two cycles of 30 seconds on and 30 seconds off). After these initial 2 minutes, the current output ceases entirely for the remainder of the 8-hour sleep period.

Sponsors & Collaborators

• Xidian University

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

BASIC_SCIENCE

Masking

DOUBLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

35 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2026-06-16

Primary Completion

2026-07-30

Completion

2026-07-31

Countries

• China

Study Locations