Clinical trials data

Symbol Coding in sleep trials: 89 registered studies

Every registered sleep and sleep disorders study on ClinicalTrials.gov that names Symbol Coding in an outcome measure: how often it is a primary outcome, the tests named with it, how large the studies are and when they measure it.

Registered sleep and sleep disorders studies name it in an outcome measure: 89
Name it in a primary outcome, 33%: 29 of 89
Of the condition's 749 studies name it, against 9% of all registered studies: 12%; Other conditions
Median participants per study: 60; By phase

Try the Symbol Key Game Try Symbol Coding

Tests named in the same studies

The library tests that sleep and sleep disorders studies naming Symbol Coding name most often beside it.

1
Psychomotor Vigilance Task35 studies, 21 as a primary outcome
2
Trail Making Test18 studies, 6 as a primary outcome
3
N-Back Task14 studies, 12 as a primary outcome
4
Verbal Learning12 studies, 3 as a primary outcome
5
Digit Span Test11 studies, 4 as a primary outcome
6
Stroop Color-Word Test10 studies, 3 as a primary outcome
7
Verbal Fluency8 studies, 3 as a primary outcome
8
Balloon Risk6 studies, 4 as a primary outcome
9
Paced Visual Serial Addition Test6 studies, 4 as a primary outcome
10
Selective Reminding Task6 studies, 0 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Studies by start year

Each study counted once. 2026 is partly planned starts.

A test as a primary outcomeOnly in secondary or other outcomes

Show as a table

Registered studies by start year
Start year	Studies	A test as a primary outcome
2000	0	0
2001	0	0
2002	0	0
2003	1	0
2004	5	0
2005	2	0
2006	1	1
2007	4	0
2008	3	1
2009	4	0
2010	3	0
2011	2	1
2012	1	0
2013	3	0
2014	0	0
2015	3	2
2016	2	1
2017	4	1
2018	5	4
2019	7	3
2020	4	3
2021	4	2
2022	6	1
2023	5	3
2024	9	3
2025	4	2
2026	7	1

Phases and study sizes

By phase

Phase 14 studies, 2 as a primary outcome
Phase 212 studies, 2 as a primary outcome
Phase 313 studies, 0 as a primary outcome
Phase 48 studies, 2 as a primary outcome
Not applicable42 studies, 18 as a primary outcome
Observational10 studies, 5 as a primary outcome

Participants per study

Phase 267 median, 44 to 126
Phase 391 median, 40 to 309
Not applicable59 median, 25 to 120
Observational85 median, 53 to 100

Participants per study. The bar spans the middle half of the studies in each phase, the mark is the median, and the axis is logarithmic. Phases with fewer than 10 studies that give a size are left out.

Show as a table

Participants per sleep and sleep disorders study that names Symbol Coding, by phase
Phase	Studies with a size	Median	Middle half
Phase 2	11	67	44 to 126
Phase 3	13	91	40 to 309
Not applicable	41	59	25 to 120
Observational	10	85	53 to 100

When sleep trials measure it

Half of the primary outcomes that name Symbol Coding are measured within 2 weeks of the start, and the middle half from 1 week to 4 months. 24 primary outcomes give a duration.

Latest time point of each outcome

Within a day12 outcomes, 3 as a primary outcome
Up to 4 weeks31 outcomes, 12 as a primary outcome
1 to 3 months15 outcomes, 2 as a primary outcome
3 to 6 months6 outcomes, 2 as a primary outcome
6 to 12 months7 outcomes, 4 as a primary outcome
1 to 2 years2 outcomes, 1 as a primary outcome
No duration given16 outcomes, 5 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

73 of the 89 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

Recruiting12 studies, 4 as a primary outcome
Not yet recruiting5 studies, 2 as a primary outcome
Active, not recruiting6 studies, 3 as a primary outcome
Completed54 studies, 19 as a primary outcome
Stopped early4 studies, 0 as a primary outcome
Status unknown8 studies, 1 as a primary outcome

What they test

Behavioral15 studies, 8 as a primary outcome
Drug37 studies, 5 as a primary outcome
Device14 studies, 3 as a primary outcome
Dietary supplement3 studies, 1 as a primary outcome
Diagnostic test2 studies, 2 as a primary outcome
Radiation3 studies, 2 as a primary outcome
Combination product1 studies, 1 as a primary outcome
Other14 studies, 6 as a primary outcome
None given5 studies, 2 as a primary outcome

Intervention types as registered. A study can list several; observational studies often list none.

25 countries in all. A study with sites in several counts in each; 8 list no site.

Reported results

Completed studies with results posted on ClinicalTrials.gov, a results paper the registry links to the study, or both.

Completed sleep and sleep disorders studies that name Symbol Coding: 30 of 54, 56%

Every completed study with a cognitive outcome: 3,626 of 7,953, 46%

Completed sleep and sleep disorders studies that name Symbol Coding and every completed study, by how they reported results
Results	Completed sleep and sleep disorders studies that name Symbol Coding	Every completed study
Results on ClinicalTrials.gov and a paper	9, 17%	776, 10%
Results on ClinicalTrials.gov only	7, 13%	1,139, 14%
A results paper only	14, 26%	1,711, 22%
Neither	24, 44%	4,327, 54%

The 89 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.

89 studies match. 29 name Symbol Coding in a primary outcome. Median size 60 participants. Median time to the primary outcome: 2 weeks.

Loading 89 studies; the filters turn on when they arrive.

By start year

2026 is partly planned starts.

Show as a table

Matching studies by start year
Start year	Studies	As a primary outcome
2000	0	0
2001	0	0
2002	0	0
2003	1	0
2004	5	0
2005	2	0
2006	1	1
2007	4	0
2008	3	1
2009	4	0
2010	3	0
2011	2	1
2012	1	0
2013	3	0
2014	0	0
2015	3	2
2016	2	1
2017	4	1
2018	5	4
2019	7	3
2020	4	3
2021	4	2
2022	6	1
2023	5	3
2024	9	3
2025	4	2
2026	7	1

Library tests named most

Largest condition groups

Sleep and sleep disorders89 studies, 29 as a primary outcome
Pain and fatigue10 studies, 6 as a primary outcome
Depression and bipolar disorder8 studies, 4 as a primary outcome
Multiple sclerosis6 studies, 3 as a primary outcome
Anxiety, PTSD and OCD5 studies, 4 as a primary outcome
Obesity and diabetes4 studies, 2 as a primary outcome
Dementia and Alzheimer's3 studies, 0 as a primary outcome
Aging, frailty and exercise3 studies, 1 as a primary outcome
Mild cognitive impairment2 studies, 2 as a primary outcome
ADHD2 studies, 0 as a primary outcome
Cancer2 studies, 1 as a primary outcome
Healthy volunteers2 studies, 0 as a primary outcome

Phases

Participants

Lead sponsor: industry 29, other 60. Interventional 79, observational 10.

As a primary outcomeSecondary or other outcomeSymbol Coding

The studies, newest registration first

Each number opens the study's record on ClinicalTrials.gov.

Registered studies that match the filters, newest registration first, with the library tests each one names and the outcome list that names them.
Study	Start	Phase	Conditions	Participants	Lead sponsor	Status	Library tests named, with the latest time point
NCT07897474	Start2026	PhaseObservational	ConditionsSleep and sleep disorders	Participants100	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestPrimary Stroop Color-Word TestPrimary Digit Span TestPrimary Symbol CodingPrimary Psychomotor Vigilance TaskPrimary
NCT07827651	Start2025	PhaseNot applicable	ConditionsHealthy volunteers, Aging, frailty and exercise, Sleep and sleep disorders	Participants64	Lead sponsorIndustry	StatusActive, not recruiting	Library tests named Symbol CodingSecondary12 weeks
NCT07799753	Start2026	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants50	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestSecondary4 weeks Stroop Color-Word TestSecondary4 weeks Digit Span TestSecondary4 weeks Symbol CodingSecondary4 weeks
NCT07714772	Start2026	PhaseObservational	ConditionsParkinson's disease, Sleep and sleep disorders	Participants50	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestSecondary2 weeks Symbol CodingSecondary2 weeks
NCT07633392	Start2026	PhaseNot applicable	ConditionsAging, frailty and exercise, Substance use and addiction, Sleep and sleep disorders, Cardiovascular disease	Participants240	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary4 months Symbol CodingSecondary4 months
NCT07608614	Start2025	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants16	Lead sponsorOther	StatusRecruiting	Library tests named Digit Span TestSecondary Symbol CodingSecondary Go/No-Go TaskSecondary Psychomotor Vigilance TaskSecondary
NCT07555379	Start2026	PhaseNot applicable	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants40	Lead sponsorOther	StatusNot yet recruiting	Library tests named Symbol CodingSecondary4 weeks
NCT07542756	Start2026	PhasePhase 4	ConditionsSleep and sleep disorders	Participants1,200	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingSecondary6 months Psychomotor Vigilance TaskSecondary6 months
NCT07426991	Start2024	PhaseObservational	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants837	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary18 months
NCT07363720	Start2026	PhasePhase 3	ConditionsSleep and sleep disorders	Participants98	Lead sponsorIndustry	StatusActive, not recruiting	Library tests named Symbol CodingSecondary4 months Psychomotor Vigilance TaskSecondary4 months
NCT07118904	Start2025	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants12	Lead sponsorOther	StatusCompleted	Library tests named Stroop Color-Word TestPrimary1 week Symbol CodingPrimary1 week
NCT06893224	Start2024	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants60	Lead sponsorOther	StatusActive, not recruiting	Library tests named Symbol CodingPrimarysame day Cancellation TestPrimarysame day
NCT06773416	Start2025	PhaseNot applicable	ConditionsMild cognitive impairment, Aging, frailty and exercise, Sleep and sleep disorders	Participants206	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestPrimary7 months Verbal LearningPrimary7 months Digit Span TestPrimary7 months Symbol CodingPrimary7 months Letter-Number Sequencing TaskPrimary7 months
NCT06685341	Start2019	PhasePhase 1	ConditionsSleep and sleep disorders	Participants20	Lead sponsorIndustry	StatusCompleted	Library tests named Symbol CodingPrimary4 weeks Choice Reaction TimePrimary4 weeks
NCT06553235	Start2024	PhaseNot applicable	ConditionsCancer, Sleep and sleep disorders	Participants84	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary8 months Stroop Color-Word TestSecondary8 months Verbal LearningSecondary8 months Verbal FluencySecondary8 months Digit Span TestSecondary8 months Symbol CodingSecondary8 months Continuous Performance TestPrimary8 months Psychomotor Vigilance TaskSecondary8 months Paced Visual Serial Addition TestSecondary8 months
NCT06496282	Start2024	PhasePhase 3	ConditionsSleep and sleep disorders	Participants50	Lead sponsorOther	StatusStatus unknown	Library tests named Symbol CodingSecondary6 weeks
NCT06266611	Start2024	PhasePhase 2	ConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCD, Pain and fatigue	Participants185	Lead sponsorOther	StatusRecruiting	Library tests named Stroop Color-Word TestPrimary8 weeks Symbol CodingPrimary8 weeks Continuous Performance TestPrimary8 weeks
NCT06260254	Start2024	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants23	Lead sponsorOther	StatusCompleted	Library tests named Symbol CodingSecondary N-Back TaskSecondary Psychomotor Vigilance TaskSecondary Matrix ReasoningSecondary Balloon RiskSecondary
NCT06243172	Start2024	PhaseObservational	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants60	Lead sponsorOther	StatusStatus unknown	Library tests named Trail Making TestSecondarysame day Verbal LearningSecondarysame day Verbal FluencySecondarysame day Symbol CodingSecondarysame day Letter-Number Sequencing TaskSecondarysame day
NCT06113666	Start2023	PhaseNot applicable	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants550	Lead sponsorOther	StatusActive, not recruiting	Library tests named Symbol CodingSecondary9 weeks Continuous Performance TestSecondary9 weeks
NCT06052514	Start2024	PhaseObservational	ConditionsSleep and sleep disorders, COVID-19 and long COVID	Participants22	Lead sponsorOther	StatusCompleted	Library tests named Stroop Color-Word TestSecondary6 weeks Verbal FluencySecondary6 weeks Digit Span TestSecondary6 weeks Symbol CodingSecondary6 weeks Psychomotor Vigilance TaskSecondary6 weeks
NCT06032377	Start2023	PhaseNot applicable	ConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCD	Participants275	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary6 months Stroop Color-Word TestSecondary6 months Verbal LearningSecondary6 months Verbal FluencySecondary6 months Digit Span TestSecondary6 months Symbol CodingSecondary6 months Picture Naming TestSecondary6 months Short Story RecallSecondary6 months Paired Associate LearningSecondary6 months Rapid Visual Information ProcessingSecondary6 months Intra/Extra Dimensional Set ShiftPrimary6 months Pattern Recognition MemorySecondary6 months
NCT05956392	Start2023	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants150	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary N-Back TaskPrimary Psychomotor Vigilance TaskPrimary4 weeks Symbol Scan TaskPrimary4 weeks
NCT05775627	Start2023	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants20	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary2 weeks Psychomotor Vigilance TaskPrimary2 weeks
NCT05611619	Start2023	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants45	Lead sponsorOther	StatusCompleted	Library tests named Symbol CodingPrimary N-Back TaskPrimary Psychomotor Vigilance TaskPrimary Matrix ReasoningPrimary Balloon RiskPrimary

Questions, answered from the data

How many sleep trials use Symbol Coding?

89 registered sleep and sleep disorders studies on ClinicalTrials.gov name it in an outcome measure, 29 of them in a primary outcome: 12% of the condition's 749 studies with a cognitive outcome, against 9% of all of them. It is the 3rd most named test in sleep trials.

Which tests do sleep trials use with Symbol Coding?

The Psychomotor Vigilance Task (35 studies), the Trail Making Test (18 studies) and the N-Back Task (14 studies).

How many participants do phase 2 sleep trials that use Symbol Coding enroll?

Half of the phase 2 studies that name it enroll 67 participants or fewer, and the middle half enroll 44 to 126. 11 of them give a size.

When do sleep trials measure Symbol Coding?

Half of the primary outcomes that name Symbol Coding are measured within 2 weeks of the start, and the middle half from 1 week to 4 months. 24 primary outcomes give a duration.

How many completed sleep trials that use Symbol Coding have reported results?

30 of the 54 completed studies that name it, 56%, have reported results: 16 posted them on ClinicalTrials.gov, 23 have a results paper linked to the registry record, and 9 did both. The other 24 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

How the studies are counted

For each test family, the census runs ClinicalTrials.gov's own outcome search for the family's names and reads every study first posted by the day the family was counted. These studies were read on 10 November 2026. A study counts once on a page, however many tests it names. Counts for a test cover every version of the task under any of its names, so a page can count studies that used a commercial version.

The census adds two things to each record and changes nothing in it: which outcome list names the test (primary, then secondary, then other), and the condition groups, matched on the study's condition names and MeSH terms. A study can fall in several groups; one whose only condition is cognitive impairment or decline falls in “Cognitive impairment and decline”. Studies that name only instruments outside the library count in every total and share but are not listed.

A second read on 10 November 2026 added each study's overall status, whether results are posted, its intervention types, the countries of its sites and the time frame of the outcome that names each test. A time frame counts by the latest time point it names: “Baseline, 12 and 24 weeks” is 24 weeks, a single visit is within a day, and one that names no duration, such as “end of treatment”, is left out of the timings.

A third read on 10 November 2026 added the papers the registry links to each study: those its sponsor lists as reporting results, and those PubMed links to it through the study's NCT number. A study has a results paper when one of them came out in or after the month of its primary completion and PubMed does not class it as a protocol, review or comment. A paper that never gives the NCT number is not linked, so some studies counted as reporting neither did publish.

Source: ClinicalTrials.gov, a database of the U.S. National Library of Medicine, which does not endorse these pages. Every study line is in the data release 2.1.0, and the explorer's own file is clinical-trials-studies.json.

The census counts Symbol Key Game and Symbol Coding as one test family, so this page counts their studies together.

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Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.

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Clinical trials data

Symbol Coding in sleep trials: 89 registered studies

Registered sleep and sleep disorders studies name it in an outcome measure: 89
Name it in a primary outcome, 33%: 29 of 89
Of the condition's 749 studies name it, against 9% of all registered studies: 12%; Other conditions
Median participants per study: 60; By phase

Try the Symbol Key Game Try Symbol Coding

Tests named in the same studies

The library tests that sleep and sleep disorders studies naming Symbol Coding name most often beside it.

1
Psychomotor Vigilance Task35 studies, 21 as a primary outcome
2
Trail Making Test18 studies, 6 as a primary outcome
3
N-Back Task14 studies, 12 as a primary outcome
4
Verbal Learning12 studies, 3 as a primary outcome
5
Digit Span Test11 studies, 4 as a primary outcome
6
Stroop Color-Word Test10 studies, 3 as a primary outcome
7
Verbal Fluency8 studies, 3 as a primary outcome
8
Balloon Risk6 studies, 4 as a primary outcome
9
Paced Visual Serial Addition Test6 studies, 4 as a primary outcome
10
Selective Reminding Task6 studies, 0 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Studies by start year

Each study counted once. 2026 is partly planned starts.

A test as a primary outcomeOnly in secondary or other outcomes

Show as a table

Registered studies by start year
Start year	Studies	A test as a primary outcome
2000	0	0
2001	0	0
2002	0	0
2003	1	0
2004	5	0
2005	2	0
2006	1	1
2007	4	0
2008	3	1
2009	4	0
2010	3	0
2011	2	1
2012	1	0
2013	3	0
2014	0	0
2015	3	2
2016	2	1
2017	4	1
2018	5	4
2019	7	3
2020	4	3
2021	4	2
2022	6	1
2023	5	3
2024	9	3
2025	4	2
2026	7	1

Phases and study sizes

By phase

Phase 14 studies, 2 as a primary outcome
Phase 212 studies, 2 as a primary outcome
Phase 313 studies, 0 as a primary outcome
Phase 48 studies, 2 as a primary outcome
Not applicable42 studies, 18 as a primary outcome
Observational10 studies, 5 as a primary outcome

Participants per study

Phase 267 median, 44 to 126
Phase 391 median, 40 to 309
Not applicable59 median, 25 to 120
Observational85 median, 53 to 100

Show as a table

Participants per sleep and sleep disorders study that names Symbol Coding, by phase
Phase	Studies with a size	Median	Middle half
Phase 2	11	67	44 to 126
Phase 3	13	91	40 to 309
Not applicable	41	59	25 to 120
Observational	10	85	53 to 100

When sleep trials measure it

Half of the primary outcomes that name Symbol Coding are measured within 2 weeks of the start, and the middle half from 1 week to 4 months. 24 primary outcomes give a duration.

Latest time point of each outcome

Within a day12 outcomes, 3 as a primary outcome
Up to 4 weeks31 outcomes, 12 as a primary outcome
1 to 3 months15 outcomes, 2 as a primary outcome
3 to 6 months6 outcomes, 2 as a primary outcome
6 to 12 months7 outcomes, 4 as a primary outcome
1 to 2 years2 outcomes, 1 as a primary outcome
No duration given16 outcomes, 5 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

73 of the 89 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

Recruiting12 studies, 4 as a primary outcome
Not yet recruiting5 studies, 2 as a primary outcome
Active, not recruiting6 studies, 3 as a primary outcome
Completed54 studies, 19 as a primary outcome
Stopped early4 studies, 0 as a primary outcome
Status unknown8 studies, 1 as a primary outcome

What they test

Behavioral15 studies, 8 as a primary outcome
Drug37 studies, 5 as a primary outcome
Device14 studies, 3 as a primary outcome
Dietary supplement3 studies, 1 as a primary outcome
Diagnostic test2 studies, 2 as a primary outcome
Radiation3 studies, 2 as a primary outcome
Combination product1 studies, 1 as a primary outcome
Other14 studies, 6 as a primary outcome
None given5 studies, 2 as a primary outcome

Intervention types as registered. A study can list several; observational studies often list none.

25 countries in all. A study with sites in several counts in each; 8 list no site.

Reported results

Completed studies with results posted on ClinicalTrials.gov, a results paper the registry links to the study, or both.

Completed sleep and sleep disorders studies that name Symbol Coding: 30 of 54, 56%

Every completed study with a cognitive outcome: 3,626 of 7,953, 46%

Completed sleep and sleep disorders studies that name Symbol Coding and every completed study, by how they reported results
Results	Completed sleep and sleep disorders studies that name Symbol Coding	Every completed study
Results on ClinicalTrials.gov and a paper	9, 17%	776, 10%
Results on ClinicalTrials.gov only	7, 13%	1,139, 14%
A results paper only	14, 26%	1,711, 22%
Neither	24, 44%	4,327, 54%

The 89 studies

Filter by phase, sponsor, status, country, intervention, outcome list, size and start year. Each study links to its record on ClinicalTrials.gov.

89 studies match. 29 name Symbol Coding in a primary outcome. Median size 60 participants. Median time to the primary outcome: 2 weeks.

Loading 89 studies; the filters turn on when they arrive.

By start year

2026 is partly planned starts.

Show as a table

Matching studies by start year
Start year	Studies	As a primary outcome
2000	0	0
2001	0	0
2002	0	0
2003	1	0
2004	5	0
2005	2	0
2006	1	1
2007	4	0
2008	3	1
2009	4	0
2010	3	0
2011	2	1
2012	1	0
2013	3	0
2014	0	0
2015	3	2
2016	2	1
2017	4	1
2018	5	4
2019	7	3
2020	4	3
2021	4	2
2022	6	1
2023	5	3
2024	9	3
2025	4	2
2026	7	1

Library tests named most

Largest condition groups

Sleep and sleep disorders89 studies, 29 as a primary outcome
Pain and fatigue10 studies, 6 as a primary outcome
Depression and bipolar disorder8 studies, 4 as a primary outcome
Multiple sclerosis6 studies, 3 as a primary outcome
Anxiety, PTSD and OCD5 studies, 4 as a primary outcome
Obesity and diabetes4 studies, 2 as a primary outcome
Dementia and Alzheimer's3 studies, 0 as a primary outcome
Aging, frailty and exercise3 studies, 1 as a primary outcome
Mild cognitive impairment2 studies, 2 as a primary outcome
ADHD2 studies, 0 as a primary outcome
Cancer2 studies, 1 as a primary outcome
Healthy volunteers2 studies, 0 as a primary outcome

Phases

Participants

Lead sponsor: industry 29, other 60. Interventional 79, observational 10.

As a primary outcomeSecondary or other outcomeSymbol Coding

The studies, newest registration first

Each number opens the study's record on ClinicalTrials.gov.

Registered studies that match the filters, newest registration first, with the library tests each one names and the outcome list that names them.
Study	Start	Phase	Conditions	Participants	Lead sponsor	Status	Library tests named, with the latest time point
NCT07897474	Start2026	PhaseObservational	ConditionsSleep and sleep disorders	Participants100	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestPrimary Stroop Color-Word TestPrimary Digit Span TestPrimary Symbol CodingPrimary Psychomotor Vigilance TaskPrimary
NCT07827651	Start2025	PhaseNot applicable	ConditionsHealthy volunteers, Aging, frailty and exercise, Sleep and sleep disorders	Participants64	Lead sponsorIndustry	StatusActive, not recruiting	Library tests named Symbol CodingSecondary12 weeks
NCT07799753	Start2026	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants50	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestSecondary4 weeks Stroop Color-Word TestSecondary4 weeks Digit Span TestSecondary4 weeks Symbol CodingSecondary4 weeks
NCT07714772	Start2026	PhaseObservational	ConditionsParkinson's disease, Sleep and sleep disorders	Participants50	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestSecondary2 weeks Symbol CodingSecondary2 weeks
NCT07633392	Start2026	PhaseNot applicable	ConditionsAging, frailty and exercise, Substance use and addiction, Sleep and sleep disorders, Cardiovascular disease	Participants240	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary4 months Symbol CodingSecondary4 months
NCT07608614	Start2025	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants16	Lead sponsorOther	StatusRecruiting	Library tests named Digit Span TestSecondary Symbol CodingSecondary Go/No-Go TaskSecondary Psychomotor Vigilance TaskSecondary
NCT07555379	Start2026	PhaseNot applicable	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants40	Lead sponsorOther	StatusNot yet recruiting	Library tests named Symbol CodingSecondary4 weeks
NCT07542756	Start2026	PhasePhase 4	ConditionsSleep and sleep disorders	Participants1,200	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingSecondary6 months Psychomotor Vigilance TaskSecondary6 months
NCT07426991	Start2024	PhaseObservational	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants837	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary18 months
NCT07363720	Start2026	PhasePhase 3	ConditionsSleep and sleep disorders	Participants98	Lead sponsorIndustry	StatusActive, not recruiting	Library tests named Symbol CodingSecondary4 months Psychomotor Vigilance TaskSecondary4 months
NCT07118904	Start2025	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants12	Lead sponsorOther	StatusCompleted	Library tests named Stroop Color-Word TestPrimary1 week Symbol CodingPrimary1 week
NCT06893224	Start2024	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants60	Lead sponsorOther	StatusActive, not recruiting	Library tests named Symbol CodingPrimarysame day Cancellation TestPrimarysame day
NCT06773416	Start2025	PhaseNot applicable	ConditionsMild cognitive impairment, Aging, frailty and exercise, Sleep and sleep disorders	Participants206	Lead sponsorOther	StatusNot yet recruiting	Library tests named Trail Making TestPrimary7 months Verbal LearningPrimary7 months Digit Span TestPrimary7 months Symbol CodingPrimary7 months Letter-Number Sequencing TaskPrimary7 months
NCT06685341	Start2019	PhasePhase 1	ConditionsSleep and sleep disorders	Participants20	Lead sponsorIndustry	StatusCompleted	Library tests named Symbol CodingPrimary4 weeks Choice Reaction TimePrimary4 weeks
NCT06553235	Start2024	PhaseNot applicable	ConditionsCancer, Sleep and sleep disorders	Participants84	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary8 months Stroop Color-Word TestSecondary8 months Verbal LearningSecondary8 months Verbal FluencySecondary8 months Digit Span TestSecondary8 months Symbol CodingSecondary8 months Continuous Performance TestPrimary8 months Psychomotor Vigilance TaskSecondary8 months Paced Visual Serial Addition TestSecondary8 months
NCT06496282	Start2024	PhasePhase 3	ConditionsSleep and sleep disorders	Participants50	Lead sponsorOther	StatusStatus unknown	Library tests named Symbol CodingSecondary6 weeks
NCT06266611	Start2024	PhasePhase 2	ConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCD, Pain and fatigue	Participants185	Lead sponsorOther	StatusRecruiting	Library tests named Stroop Color-Word TestPrimary8 weeks Symbol CodingPrimary8 weeks Continuous Performance TestPrimary8 weeks
NCT06260254	Start2024	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants23	Lead sponsorOther	StatusCompleted	Library tests named Symbol CodingSecondary N-Back TaskSecondary Psychomotor Vigilance TaskSecondary Matrix ReasoningSecondary Balloon RiskSecondary
NCT06243172	Start2024	PhaseObservational	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants60	Lead sponsorOther	StatusStatus unknown	Library tests named Trail Making TestSecondarysame day Verbal LearningSecondarysame day Verbal FluencySecondarysame day Symbol CodingSecondarysame day Letter-Number Sequencing TaskSecondarysame day
NCT06113666	Start2023	PhaseNot applicable	ConditionsMultiple sclerosis, Sleep and sleep disorders, Pain and fatigue	Participants550	Lead sponsorOther	StatusActive, not recruiting	Library tests named Symbol CodingSecondary9 weeks Continuous Performance TestSecondary9 weeks
NCT06052514	Start2024	PhaseObservational	ConditionsSleep and sleep disorders, COVID-19 and long COVID	Participants22	Lead sponsorOther	StatusCompleted	Library tests named Stroop Color-Word TestSecondary6 weeks Verbal FluencySecondary6 weeks Digit Span TestSecondary6 weeks Symbol CodingSecondary6 weeks Psychomotor Vigilance TaskSecondary6 weeks
NCT06032377	Start2023	PhaseNot applicable	ConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCD	Participants275	Lead sponsorOther	StatusRecruiting	Library tests named Trail Making TestSecondary6 months Stroop Color-Word TestSecondary6 months Verbal LearningSecondary6 months Verbal FluencySecondary6 months Digit Span TestSecondary6 months Symbol CodingSecondary6 months Picture Naming TestSecondary6 months Short Story RecallSecondary6 months Paired Associate LearningSecondary6 months Rapid Visual Information ProcessingSecondary6 months Intra/Extra Dimensional Set ShiftPrimary6 months Pattern Recognition MemorySecondary6 months
NCT05956392	Start2023	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants150	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary N-Back TaskPrimary Psychomotor Vigilance TaskPrimary4 weeks Symbol Scan TaskPrimary4 weeks
NCT05775627	Start2023	PhaseNot applicable	ConditionsObesity and diabetes, Sleep and sleep disorders	Participants20	Lead sponsorOther	StatusRecruiting	Library tests named Symbol CodingPrimary2 weeks Psychomotor Vigilance TaskPrimary2 weeks
NCT05611619	Start2023	PhaseNot applicable	ConditionsSleep and sleep disorders	Participants45	Lead sponsorOther	StatusCompleted	Library tests named Symbol CodingPrimary N-Back TaskPrimary Psychomotor Vigilance TaskPrimary Matrix ReasoningPrimary Balloon RiskPrimary

Questions, answered from the data

How many sleep trials use Symbol Coding?

Which tests do sleep trials use with Symbol Coding?

The Psychomotor Vigilance Task (35 studies), the Trail Making Test (18 studies) and the N-Back Task (14 studies).

How many participants do phase 2 sleep trials that use Symbol Coding enroll?

Half of the phase 2 studies that name it enroll 67 participants or fewer, and the middle half enroll 44 to 126. 11 of them give a size.

When do sleep trials measure Symbol Coding?

Half of the primary outcomes that name Symbol Coding are measured within 2 weeks of the start, and the middle half from 1 week to 4 months. 24 primary outcomes give a duration.

How many completed sleep trials that use Symbol Coding have reported results?

How the studies are counted

The census counts Symbol Key Game and Symbol Coding as one test family, so this page counts their studies together.

Run Symbol Coding in your trial

Choose tests with a record in registered trials, and run them in a browser at every site, on the same version each visit.

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Symbol Coding in sleep trials: 89 registered studies

Tests named in the same studies

Studies by start year

Phases and study sizes

By phase

Participants per study

When sleep trials measure it

Latest time point of each outcome

Status, results, interventions and countries

Status

What they test

Where their sites are

Reported results

The 89 studies

Library tests named most

Largest condition groups

Phases

Participants

The studies, newest registration first

Questions, answered from the data

How many sleep trials use Symbol Coding?

Which tests do sleep trials use with Symbol Coding?

How many participants do phase 2 sleep trials that use Symbol Coding enroll?

When do sleep trials measure Symbol Coding?

How many completed sleep trials that use Symbol Coding have reported results?

More on Symbol Coding and sleep and sleep disorders

Symbol Coding in other conditions

Other tests in sleep trials

How the studies are counted

Run Symbol Coding in your trial

Symbol Coding in sleep trials: 89 registered studies

Tests named in the same studies

Studies by start year

Phases and study sizes

By phase

Participants per study

When sleep trials measure it

Latest time point of each outcome

Status, results, interventions and countries

Status

What they test

Where their sites are

Reported results

The 89 studies

Library tests named most

Largest condition groups

Phases

Participants

The studies, newest registration first

Questions, answered from the data

How many sleep trials use Symbol Coding?

Which tests do sleep trials use with Symbol Coding?

How many participants do phase 2 sleep trials that use Symbol Coding enroll?

When do sleep trials measure Symbol Coding?

How many completed sleep trials that use Symbol Coding have reported results?

More on Symbol Coding and sleep and sleep disorders

Symbol Coding in other conditions

Other tests in sleep trials

How the studies are counted

Run Symbol Coding in your trial