SleepNCT06938672
Evaluating the Effects of tDCS on Sleep and Cognition in Healthy Older Adults
A study testing Active Transcranial Direct Current Stimulation (tDCS) in people with Sleep and Cognition, run by Northumbria University at 1 site in United Kingdom.
Trial summary
The goal of this interventional study is to learn if transcranial direct current stimulation (tDCS), a gentle, cost-effective and non-invasive brain stimulation technique can improve sleep brain activity during an afternoon nap. Read more about this study
- Who is it for?
- Ages 60 years and olderHealthy volunteers can take part
- Conditions the study is for
- Sleep, Cognition, Healthy Aging
- What is being tested?
- Active Transcranial Direct Current Stimulation (tDCS)
- Type of treatment
- Medical device
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 12 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 1 Jul 2025to 6 May 2026
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 60 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Aged 60+ years
- Speak fluent English
- Be cognitively healthy
- A self-reported good sleeper, with a regular sleep pattern
Who cannot join
- The presence of any major physical or psychiatric illness or comorbidities
- Self-reported neurodegenerative dementia or other neurological disorders
- Self-reported relevant sleep disorders or disturbances
- Those with irregular sleep schedules (i.e. night shift workers)
- A PSQI score above 5 (as this is associated with significant sleep disturbance)
- Relevant skin allergies
- Taking medication that affects the central nervous system or sleep, or consume caffeine, alcohol or cigarettes excessively
- Metallic or electronic implants
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Northumbria University
Newcastle upon Tyne, NE1 8ST
About this study
Official title: Evaluating the Effects of tDCS on Sleep and Cognition in Healthy Older Adults: A Randomised Controlled Trial Using a Nap Design
The goal of this interventional study is to learn if transcranial direct current stimulation (tDCS), a gentle, cost-effective and non-invasive brain stimulation technique can improve sleep brain activity during an afternoon nap. Since these sleep brain patterns are linked to better memory, attention, and thinking skills, this study aims to find out if improving sleep in a nap can also enhance these cognitive skills in healthy older adults (aged 60+).
The main questions it aims to answer are:
Read more
- Can a short (20-minute) tDCS session before a nap improve sleep patterns during the nap?
- Since these sleep patterns are linked to memory and attention, can tDCS also improve thinking skills after the nap?
- Are two tDCS session more effective than one for improving nap sleep and thinking skills?
Participants will:
- Be required to come to the university for testing over four days.
During each session they will:
- Complete computer based-tasks to assess memory and thinking.
- Receive a 20-minute session of either real (active) or fake (placebo) tDCS.
- Take a short, monitored nap while researchers measure sleep activity (using polysomnography - a gold-standard, non-invasive sleep monitoring tool).
- Complete an easy-to-use sleep test at home on the nights after the naps.
- Wear a lightweight watch (called an Actiwatch) throughout the study period to track sleep and movement.
- Complete daily sleep diaries.
By taking part, participants will help researchers understand whether tDCS can improve sleep during naps and, in turn, support memory and thinking skills. This research could lead to better treatments for sleep problems, help protect brain health, and reduce the risk of dementia as people age. The brain stimulation in this study may also help improve their sleep and cognition.
Read the detailed description
Sleep is vital for maintaining physical and cognitive health across the lifespan. However, normal age-related changes to sleep can impair memory, learning, and waste clearance in the brain, contributing to the risk of cognitive decline and dementia.
Transcranial direct current stimulation (tDCS), a non-invasive technique that modulates brain activity, shows promise for enhancing both sleep and cognition. However, existing studies have significant methodological limitations. Notably, very few have investigated 'offline' tDCS -where stimulation is applied before sleep- to assess objective sleep changes using polysomnography (PSG). Instead, most research has relied on subjective measures, consistently finding that offline tDCS enhances perceived sleep quality, especially with repeated stimulation sessions. Importantly, offline tDCS may be more feasible for use outside laboratory settings compared to 'online' approaches, where stimulation is applied during sleep, making it a more scalable intervention.
Furthermore, delivering tDCS before a daytime nap, rather than nocturnal sleep, offers additional advantages by reducing participant burden, particularly in older adults. Studies applying tDCS during a nap in older adults have shown improvements in objective sleep microstructure and declarative memory. By contrast, studies applying tDCS during nocturnal sleep have reported inconsistent results. Despite its potential benefits, no studies have explored the effects of an offline, nap-based tDCS approach on objective sleep outcomes.
Additionally, few studies have examined whether repeated sessions of offline tDCS might amplify its effects on objective PSG-measured sleep. While repeated sessions have been shown to positively influence subjective sleep outcomes, it remains unclear whether the same benefits apply to objective sleep metrics. This study will address this gap by investigating whether two sessions of offline tDCS, compared to one, are necessary to improve objective sleep outcomes.
In summary, this study aims to determine whether offline tDCS applied prior to a nap can enhance objective sleep during a daytime nap and improve post-nap cognitive performance in older adults. If effective, this low-burden, non-invasive intervention could serve as a practical tool for promoting healthy aging and reducing dementia risk.
The primary objectives of this randomised, placebo-controlled crossover trial are:
To evaluate the impact of offline tDCS on objective sleep microstructure and architecture during naps.
To assess the effects of tDCS on post-nap cognitive performance. To examine the cumulative effect of two tDCS sessions upon objective sleep and cognition, compared to one.
- Conditions
- Sleep, Cognition, Healthy Aging
- Being tested
- Placebo Transcranial Direct Current Stimulation (tDCS), Active Transcranial Direct Current Stimulation (tDCS)
- Keywords
- sleep, healthy aging, cognition, tDCS, non-invasive brain stimulation, nap
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Placebo Transcranial Direct Current Stimulation (tDCS)Device
Also called sham tDCS
Placebo Transcranial direct current stimulation (tDCS): Participants will experience a 20-minute session of placebo tDCS on two consecutive days.
Active Transcranial Direct Current Stimulation (tDCS)Device
Also called tDCS
Active transcranial direct current stimulation (tDCS). Participants will experience a 20-minute session of active tDCS (1.2 mA) on two consecutive days.
| Study group | Role | What they receive |
|---|---|---|
| Active Transcranial Direct Current Stimulation (tDCS) | Active comparator | Transcranial direct current stimulation. Participants will experience a 20-minute session of active tDCS (1.2 mA) on two consecutive days. Receives: Device: Active Transcranial Direct Current Stimulation (tDCS) |
| Placebo Transcranial Direct Current Stimulation (tDCS) | Placebo comparator | Transcranial direct current stimulation. Participants will experience a 20-minute session of placebo tDCS on two consecutive days. Receives: Device: Placebo Transcranial Direct Current Stimulation (tDCS) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Sleep spindle density
PSG-measured slow (11.99 - 12.99Hz) and fast (13 - 14.99Hz) sleep spindle density
Measured: During nap immediately after tDCS application
Sleep spindle amplitude
PSG-measured slow (11.99 - 12.99Hz) and fast (13 - 14.99Hz) sleep spindle amplitude
Measured: During nap immediately after tDCS application
Slow wave sleep amplitude
PSG-measured SWS amplitude (peak-to-peak, μV)
Measured: During nap immediately after tDCS application
Slow wave sleep density
PSG-measured slow wave sleep density (number of slow waves divided by the minutes of sleep)
Measured: During nap immediately after tDCS application
Verbal declarative memory
Change in Verbal Paired Associates Word Learning Task performance will be measured by % correct recall at baseline (before the tDCS intervention and nap) compared to % correct recall 15 minutes after the nap has taken place.
Measured: Baseline (before tDCS/nap) and 15 minutes after the nap
Attentional Network Task (ANT)
Change in Attentional Network Task performance will be measured by Reaction Time (RT) (Milliseconds (ms) at baseline (before the tDCS intervention and nap) compared to RT (ms) 15 minutes after the nap has taken place.
Measured: Baseline (before tDCS/nap) and 15 minutes after the nap
Attentional Network Task (ANT)
Change in Attentional Network Task performance will be measured by Accuracy (%) at baseline (before the tDCS intervention and nap) compared to Accuracy (%) 15 minutes after the nap has taken place.
Measured: Baseline (before tDCS/nap) and 15 minutes after the nap
Secondary outcomes (2)
Visuo-spatial declarative picture memory
Change in Picture Memory performance will be measured by Accuracy (% Correct) at baseline (before the tDCS intervention and nap) compared to Accuracy (% Correct) 15 minutes after the nap has taken place.
Measured: Baseline (before tDCS/nap) and 15 minutes after the nap
Visuo-spatial declarative location memory
Change in Location Memory performance will be measured by Accuracy (% Correct) at baseline (before the tDCS intervention and nap) compared to Accuracy (% Correct) 15 minutes after the nap has taken place
Measured: Baseline (before tDCS/nap) and 15 minutes after the nap
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Apr 2025
- Study start1 Jul 2025
- Primary completion6 May 2026
- Study completion6 May 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for SleepStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- Northumbria University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Rosie H Musgrave, BA Hons, RPSGT, Principal investigator, Northumbria University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06938672
- Sponsor's protocol ID
- 2025-6636-10284
- Status last verified
- May 2026
- First submitted
- 13 Mar 2025
- Last updated
- 7 May 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 7 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluating the Effects of tDCS on Sleep and Cognition in Healthy Older Adults: A Randomised Controlled Trial Using a Nap Design
- ClinicalTrials.gov ID
- NCT06938672
- Acronym / sponsor ID
- 2025-6636-10284
- Conditions
- Sleep, Cognition, Healthy Aging
- Keywords
- sleep, healthy aging, cognition, tDCS, non-invasive brain stimulation, nap
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 12 participants (actual)
- Lead sponsor
- Northumbria UniversityUniversity, hospital or other
- Study start
- 1 Jul 2025 (actual)
- Primary completion
- 6 May 2026 (actual)
- Study completion
- 6 May 2026 (actual)
- First posted
- 22 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this interventional study is to learn if transcranial direct current stimulation (tDCS), a gentle, cost-effective and non-invasive brain stimulation technique can improve sleep brain activity during an afternoon nap. Since these sleep brain patterns are linked to better memory, attention, and thinking skills, this study aims to find out if improving sleep in a nap can also enhance these cognitive skills in healthy older adults (aged 60+).
The main questions it aims to answer are:
- Can a short (20-minute) tDCS session before a nap improve sleep patterns during the nap?
- Since these sleep patterns are linked to memory and attention, can tDCS also improve thinking skills after the nap?
- Are two tDCS session more effective than one for improving nap sleep and thinking skills?
Participants will:
- Be required to come to the university for testing over four days.
During each session they will:
- Complete computer based-tasks to assess memory and thinking.
- Receive a 20-minute session of either real (active) or fake (placebo) tDCS.
- Take a short, monitored nap while researchers measure sleep activity (using polysomnography - a gold-standard, non-invasive sleep monitoring tool).
- Complete an easy-to-use sleep test at home on the nights after the naps.
- Wear a lightweight watch (called an Actiwatch) throughout the study period to track sleep and movement.
- Complete daily sleep diaries.
By taking part, participants will help researchers understand whether tDCS can improve sleep during naps and, in turn, support memory and thinking skills. This research could lead to better treatments for sleep problems, help protect brain health, and reduce the risk of dementia as people age. The brain stimulation in this study may also help improve their sleep and cognition.
Detailed description
Sleep is vital for maintaining physical and cognitive health across the lifespan. However, normal age-related changes to sleep can impair memory, learning, and waste clearance in the brain, contributing to the risk of cognitive decline and dementia.
Transcranial direct current stimulation (tDCS), a non-invasive technique that modulates brain activity, shows promise for enhancing both sleep and cognition. However, existing studies have significant methodological limitations. Notably, very few have investigated 'offline' tDCS -where stimulation is applied before sleep- to assess objective sleep changes using polysomnography (PSG). Instead, most research has relied on subjective measures, consistently finding that offline tDCS enhances perceived sleep quality, especially with repeated stimulation sessions. Importantly, offline tDCS may be more feasible for use outside laboratory settings compared to 'online' approaches, where stimulation is applied during sleep, making it a more scalable intervention.
Furthermore, delivering tDCS before a daytime nap, rather than nocturnal sleep, offers additional advantages by reducing participant burden, particularly in older adults. Studies applying tDCS during a nap in older adults have shown improvements in objective sleep microstructure and declarative memory. By contrast, studies applying tDCS during nocturnal sleep have reported inconsistent results. Despite its potential benefits, no studies have explored the effects of an offline, nap-based tDCS approach on objective sleep outcomes.
Additionally, few studies have examined whether repeated sessions of offline tDCS might amplify its effects on objective PSG-measured sleep. While repeated sessions have been shown to positively influence subjective sleep outcomes, it remains unclear whether the same benefits apply to objective sleep metrics. This study will address this gap by investigating whether two sessions of offline tDCS, compared to one, are necessary to improve objective sleep outcomes.
In summary, this study aims to determine whether offline tDCS applied prior to a nap can enhance objective sleep during a daytime nap and improve post-nap cognitive performance in older adults. If effective, this low-burden, non-invasive intervention could serve as a practical tool for promoting healthy aging and reducing dementia risk.
The primary objectives of this randomised, placebo-controlled crossover trial are:
To evaluate the impact of offline tDCS on objective sleep microstructure and architecture during naps.
To assess the effects of tDCS on post-nap cognitive performance. To examine the cumulative effect of two tDCS sessions upon objective sleep and cognition, compared to one.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Active Transcranial Direct Current Stimulation (tDCS) | Active comparator | Device: Active Transcranial Direct Current Stimulation (tDCS)Transcranial direct current stimulation. Participants will experience a 20-minute session of active tDCS (1.2 mA) on two consecutive days. |
| Placebo Transcranial Direct Current Stimulation (tDCS) | Placebo comparator | Device: Placebo Transcranial Direct Current Stimulation (tDCS)Transcranial direct current stimulation. Participants will experience a 20-minute session of placebo tDCS on two consecutive days. |
Who may qualify
- Ages
- 60 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Aged 60+ years
- Speak fluent English
- Be cognitively healthy
- A self-reported good sleeper, with a regular sleep pattern
Key exclusion criteria (8 listed)
- The presence of any major physical or psychiatric illness or comorbidities
- Self-reported neurodegenerative dementia or other neurological disorders
- Self-reported relevant sleep disorders or disturbances
- Those with irregular sleep schedules (i.e. night shift workers)
- A PSQI score above 5 (as this is associated with significant sleep disturbance)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Placebo Transcranial Direct Current Stimulation (tDCS)Also: sham tDCSPlacebo Transcranial direct current stimulation (tDCS): Participants will experience a 20-minute session of placebo tDCS on two consecutive days. | Device | Placebo Transcranial Direct Current Stimulation (tDCS) |
| Active Transcranial Direct Current Stimulation (tDCS)Also: tDCSActive transcranial direct current stimulation (tDCS). Participants will experience a 20-minute session of active tDCS (1.2 mA) on two consecutive days. | Device | Active Transcranial Direct Current Stimulation (tDCS) |
Primary outcome
Sleep spindle density
Time frame: During nap immediately after tDCS application
PSG-measured slow (11.99 - 12.99Hz) and fast (13 - 14.99Hz) sleep spindle density
Sleep spindle amplitude
Time frame: During nap immediately after tDCS application
PSG-measured slow (11.99 - 12.99Hz) and fast (13 - 14.99Hz) sleep spindle amplitude
Slow wave sleep amplitude
Time frame: During nap immediately after tDCS application
PSG-measured SWS amplitude (peak-to-peak, μV)
Slow wave sleep density
Time frame: During nap immediately after tDCS application
PSG-measured slow wave sleep density (number of slow waves divided by the minutes of sleep)
Verbal declarative memory
Time frame: Baseline (before tDCS/nap) and 15 minutes after the nap
Change in Verbal Paired Associates Word Learning Task performance will be measured by % correct recall at baseline (before the tDCS intervention and nap) compared to % correct recall 15 minutes after the nap has taken place.
Attentional Network Task (ANT)
Time frame: Baseline (before tDCS/nap) and 15 minutes after the nap
Change in Attentional Network Task performance will be measured by Reaction Time (RT) (Milliseconds (ms) at baseline (before the tDCS intervention and nap) compared to RT (ms) 15 minutes after the nap has taken place.
Attentional Network Task (ANT)
Time frame: Baseline (before tDCS/nap) and 15 minutes after the nap
Change in Attentional Network Task performance will be measured by Accuracy (%) at baseline (before the tDCS intervention and nap) compared to Accuracy (%) 15 minutes after the nap has taken place.
2 secondary outcomes
Visuo-spatial declarative picture memory
Time frame: Baseline (before tDCS/nap) and 15 minutes after the nap
Visuo-spatial declarative location memory
Time frame: Baseline (before tDCS/nap) and 15 minutes after the nap
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 May 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Rosie H Musgrave, BA Hons, RPSGT principal investigator
Northumbria University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Active Transcranial Direct Current Stimulation (tDCS) in people with Sleep and Cognition, run by Northumbria University at 1 site in United Kingdom.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 7 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United Kingdom. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Sleep spindle density (time frame: During nap immediately after tDCS application). The study lists 7 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 May 2026.