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  1. Home
  2. /Data
  3. /Clinical trials
  4. /Conditions
  5. /Sleep and sleep disorders
  6. /Verbal Fluency

Clinical trials data

Verbal Fluency in sleep trials: 58 registered studies

Every registered sleep and sleep disorders study on ClinicalTrials.gov that names Verbal Fluency 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
58
Name it in a primary outcome, 34%
20 of 58
Of the condition's 749 studies name it, against 11% of all registered studies
8%
Other conditions
Median participants per study
89
By phase
Try Verbal Fluency

Tests named in the same studies

The library tests that sleep and sleep disorders studies naming Verbal Fluency name most often beside it.
  1. 1

    Trail Making Test24 studies, 8 as a primary outcome

  2. 2

    Verbal Learning19 studies, 7 as a primary outcome

  3. 3

    Digit Span Test18 studies, 7 as a primary outcome

  4. 4

    Stroop Color-Word Test17 studies, 4 as a primary outcome

  5. 5

    Category Fluency10 studies, 4 as a primary outcome

  6. 6

    Psychomotor Vigilance Task9 studies, 2 as a primary outcome

  7. 7

    Symbol Coding8 studies, 3 as a primary outcome

  8. 8

    Paced Visual Serial Addition Test6 studies, 3 as a primary outcome

  9. 9

    Picture Naming Test5 studies, 1 as a primary outcome

  10. 10

    Selective Reminding Task4 studies, 1 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.
02000: 0 studies, 0 with a test as a primary outcome20002001: 0 studies, 0 with a test as a primary outcome2002: 0 studies, 0 with a test as a primary outcome2003: 0 studies, 0 with a test as a primary outcome2004: 0 studies, 0 with a test as a primary outcome2005: 2 studies, 0 with a test as a primary outcome20052006: 1 studies, 0 with a test as a primary outcome2007: 1 studies, 0 with a test as a primary outcome2008: 0 studies, 0 with a test as a primary outcome2009: 0 studies, 0 with a test as a primary outcome2010: 1 studies, 0 with a test as a primary outcome20102011: 1 studies, 0 with a test as a primary outcome2012: 1 studies, 1 with a test as a primary outcome2013: 1 studies, 0 with a test as a primary outcome2014: 1 studies, 0 with a test as a primary outcome2015: 2 studies, 1 with a test as a primary outcome20152016: 1 studies, 1 with a test as a primary outcome2017: 2 studies, 0 with a test as a primary outcome2018: 0 studies, 0 with a test as a primary outcome2019: 6 studies, 2 with a test as a primary outcome2020: 4 studies, 3 with a test as a primary outcome20202021: 4 studies, 2 with a test as a primary outcome2022: 4 studies, 0 with a test as a primary outcome2023: 5 studies, 1 with a test as a primary outcome2024: 9 studies, 4 with a test as a primary outcome2025: 6 studies, 3 with a test as a primary outcome20252026: 6 studies, 2 with a test as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

Show as a table
Registered studies by start year
Start yearStudiesA test as a primary outcome
200000
200100
200200
200300
200400
200520
200610
200710
200800
200900
201010
201110
201211
201310
201410
201521
201611
201720
201800
201962
202043
202142
202240
202351
202494
202563
202662

Phases and study sizes

By phase

  • Early phase 11 studies, 0 as a primary outcome
  • Phase 11 studies, 0 as a primary outcome
  • Phase 23 studies, 0 as a primary outcome
  • Phase 44 studies, 0 as a primary outcome
  • Not applicable32 studies, 11 as a primary outcome
  • Observational17 studies, 9 as a primary outcome

Participants per study

102050100200
  • Not applicable84 median, 48 to 136
  • Observational100 median, 65 to 165
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 Verbal Fluency, by phase
PhaseStudies with a sizeMedianMiddle half
Not applicable328448 to 136
Observational1710065 to 165

When sleep trials measure it

Half of the primary outcomes that name Verbal Fluency are measured within 12 weeks of the start, and the middle half from 2 weeks to 12 months. 19 primary outcomes give a duration.

Latest time point of each outcome

  • Within a day9 outcomes, 5 as a primary outcome
  • Up to 4 weeks7 outcomes, 1 as a primary outcome
  • 1 to 3 months15 outcomes, 5 as a primary outcome
  • 3 to 6 months10 outcomes, 2 as a primary outcome
  • 6 to 12 months9 outcomes, 3 as a primary outcome
  • 1 to 2 years3 outcomes, 2 as a primary outcome
  • Over 2 years2 outcomes, 1 as a primary outcome
  • No duration given3 outcomes, 1 as a primary outcome

A test as a primary outcomeOnly in secondary or other outcomes

55 of the 58 outcome measures give a duration. A single visit counts as within a day.

Status, results, interventions and countries

Status

  • Recruiting16 studies, 4 as a primary outcome
  • Not yet recruiting5 studies, 3 as a primary outcome
  • Active, not recruiting2 studies, 2 as a primary outcome
  • Completed25 studies, 6 as a primary outcome
  • Stopped early1 studies, 0 as a primary outcome
  • Status unknown9 studies, 5 as a primary outcome

What they test

  • Behavioral15 studies, 2 as a primary outcome
  • Drug7 studies, 0 as a primary outcome
  • Device24 studies, 9 as a primary outcome
  • Procedure2 studies, 1 as a primary outcome
  • Diagnostic test2 studies, 2 as a primary outcome
  • Biological2 studies, 1 as a primary outcome
  • Radiation1 studies, 1 as a primary outcome
  • Other10 studies, 7 as a primary outcome
  • None given8 studies, 5 as a primary outcome

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

Where their sites are

  • United States16 studies, 3 as a primary outcome
  • France7 studies, 2 as a primary outcome
  • Denmark5 studies, 1 as a primary outcome
  • Canada4 studies, 1 as a primary outcome
  • Hong Kong4 studies, 1 as a primary outcome
  • Switzerland3 studies, 0 as a primary outcome
  • Brazil2 studies, 1 as a primary outcome
  • Italy2 studies, 1 as a primary outcome
  • Norway2 studies, 0 as a primary outcome
  • Türkiye2 studies, 1 as a primary outcome
  • United Kingdom2 studies, 0 as a primary outcome
  • Argentina1 studies, 1 as a primary outcome

24 countries in all. A study with sites in several counts in each; 4 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 Verbal Fluency: 12 of 25, 48%

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

Completed sleep and sleep disorders studies that name Verbal Fluency and every completed study, by how they reported results
ResultsCompleted sleep and sleep disorders studies that name Verbal FluencyEvery completed study
Results on ClinicalTrials.gov and a paper5, 20%776, 10%
Results on ClinicalTrials.gov only3, 12%1,139, 14%
A results paper only4, 16%1,711, 22%
Neither13, 52%4,327, 54%

The 58 studies

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

58 studies match. 20 name Verbal Fluency in a primary outcome. Median size 89 participants. Median time to the primary outcome: 12 weeks.

Loading 58 studies; the filters turn on when they arrive.

By start year
02.557.5102000: 0 studies, 0 naming Verbal Fluency in a primary outcome20002001: 0 studies, 0 naming Verbal Fluency in a primary outcome2002: 0 studies, 0 naming Verbal Fluency in a primary outcome2003: 0 studies, 0 naming Verbal Fluency in a primary outcome2004: 0 studies, 0 naming Verbal Fluency in a primary outcome2005: 2 studies, 0 naming Verbal Fluency in a primary outcome20052006: 1 studies, 0 naming Verbal Fluency in a primary outcome2007: 1 studies, 0 naming Verbal Fluency in a primary outcome2008: 0 studies, 0 naming Verbal Fluency in a primary outcome2009: 0 studies, 0 naming Verbal Fluency in a primary outcome2010: 1 studies, 0 naming Verbal Fluency in a primary outcome20102011: 1 studies, 0 naming Verbal Fluency in a primary outcome2012: 1 studies, 1 naming Verbal Fluency in a primary outcome2013: 1 studies, 0 naming Verbal Fluency in a primary outcome2014: 1 studies, 0 naming Verbal Fluency in a primary outcome2015: 2 studies, 1 naming Verbal Fluency in a primary outcome20152016: 1 studies, 1 naming Verbal Fluency in a primary outcome2017: 2 studies, 0 naming Verbal Fluency in a primary outcome2018: 0 studies, 0 naming Verbal Fluency in a primary outcome2019: 6 studies, 2 naming Verbal Fluency in a primary outcome2020: 4 studies, 3 naming Verbal Fluency in a primary outcome20202021: 4 studies, 2 naming Verbal Fluency in a primary outcome2022: 4 studies, 0 naming Verbal Fluency in a primary outcome2023: 5 studies, 1 naming Verbal Fluency in a primary outcome2024: 9 studies, 4 naming Verbal Fluency in a primary outcome2025: 6 studies, 3 naming Verbal Fluency in a primary outcome20252026: 6 studies, 2 naming Verbal Fluency in a primary outcome

2026 is partly planned starts.

Show as a table
Matching studies by start year
Start yearStudiesAs a primary outcome
200000
200100
200200
200300
200400
200520
200610
200710
200800
200900
201010
201110
201211
201310
201410
201521
201611
201720
201800
201962
202043
202142
202240
202351
202494
202563
202662

Library tests named most

  • Verbal Fluency58 studies, 20 as a primary outcome
  • Trail Making Test24 studies, 8 as a primary outcome
  • Verbal Learning19 studies, 7 as a primary outcome
  • Digit Span Test18 studies, 7 as a primary outcome
  • Stroop Color-Word Test17 studies, 4 as a primary outcome
  • Category Fluency10 studies, 4 as a primary outcome
  • Psychomotor Vigilance Task9 studies, 2 as a primary outcome
  • Symbol Coding8 studies, 3 as a primary outcome
  • Paced Visual Serial Addition Test6 studies, 3 as a primary outcome
  • Picture Naming Test5 studies, 1 as a primary outcome

Largest condition groups

  • Sleep and sleep disorders58 studies, 20 as a primary outcome
  • Depression and bipolar disorder11 studies, 5 as a primary outcome
  • Dementia and Alzheimer's8 studies, 4 as a primary outcome
  • Pain and fatigue8 studies, 3 as a primary outcome
  • Aging, frailty and exercise7 studies, 3 as a primary outcome
  • Cancer6 studies, 2 as a primary outcome
  • Mild cognitive impairment5 studies, 2 as a primary outcome
  • Anxiety, PTSD and OCD5 studies, 1 as a primary outcome
  • Stroke4 studies, 0 as a primary outcome
  • Parkinson's disease4 studies, 1 as a primary outcome
  • Healthy volunteers3 studies, 0 as a primary outcome
  • Obesity and diabetes3 studies, 1 as a primary outcome

Phases

Participants

Lead sponsor: industry 3, other 55. Interventional 41, observational 17.

As a primary outcomeSecondary or other outcomeVerbal Fluency

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.
StudyStartPhaseConditionsParticipantsLead sponsorStatusLibrary tests named, with the latest time point
NCT07882433Start2026PhaseNot applicableConditionsSleep and sleep disordersParticipants50Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Digit Span TestSecondary6 months
  • Paced Visual Serial Addition TestSecondary6 months
NCT07651085Start2024PhaseObservationalConditionsDementia and Alzheimer's, Mild cognitive impairment, Parkinson's disease, Sleep and sleep disordersParticipants65Lead sponsorOtherStatusActive, not recruitingLibrary tests named
  • Verbal LearningPrimary
  • Verbal FluencyPrimary
  • Category FluencyPrimary
  • Clock Drawing TaskPrimary
NCT07556432Start2026PhaseNot applicableConditionsSleep and sleep disordersParticipants120Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Category FluencySecondary6 months
  • Selective Reminding TaskSecondary6 months
NCT07364318Start2024PhaseObservationalConditionsSleep and sleep disordersParticipants30Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimarysame day
  • Stroop Color-Word TestPrimarysame day
  • Verbal LearningPrimarysame day
  • Verbal FluencyPrimarysame day
  • Digit Span TestPrimarysame day
  • Category FluencyPrimarysame day
  • Task Switching TestPrimarysame day
NCT07355842Start2026PhaseNot applicableConditionsParkinson's disease, Sleep and sleep disordersParticipants80Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary18 months
  • Stroop Color-Word TestSecondary18 months
  • Verbal LearningSecondary18 months
  • Verbal FluencySecondary18 months
  • Digit Span TestSecondary18 months
  • Category FluencySecondary18 months
  • Picture Naming TestSecondary18 months
  • Psychomotor Vigilance TaskOther outcome18 months
  • Complex Figure Copy and RecallSecondary18 months
  • Finger Tapping TaskSecondary18 months
  • Sustained Attention to ResponseOther outcome18 months
  • Line Angle MatchingSecondary18 months
NCT07329049Start2026PhaseNot applicableConditionsSleep and sleep disordersParticipants42Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Stroop Color-Word TestPrimary8 weeks
  • Verbal FluencyPrimary8 weeks
  • Digit Span TestPrimary8 weeks
NCT07272863Start2026PhaseNot applicableConditionsDementia and Alzheimer's, Aging, frailty and exercise, Sleep and sleep disordersParticipants214Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Trail Making TestPrimary12 months
  • Verbal FluencyPrimary12 months
NCT07156708Start2025PhaseNot applicableConditionsAging, frailty and exercise, Sleep and sleep disordersParticipants98Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Stroop Color-Word TestSecondary13 weeks
  • Verbal FluencyPrimary6 months
  • Digit Span TestPrimary6 months
NCT07119268Start2025PhaseNot applicableConditionsSchizophrenia and psychosis, Sleep and sleep disordersParticipants115Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary2 weeks
NCT06968728Start2025PhaseObservationalConditionsObesity and diabetes, Sleep and sleep disordersParticipants400Lead sponsorOtherStatusNot yet recruitingLibrary tests named
  • Verbal FluencyPrimary4 years
NCT06922409Start2025PhaseNot applicableConditionsStroke, Depression and bipolar disorder, Sleep and sleep disorders, Pain and fatigueParticipants45Lead sponsorOtherStatusRecruitingLibrary tests named
  • Stroop Color-Word TestSecondary1 week
  • Verbal FluencySecondary1 week
  • Category FluencySecondary1 week
NCT06847074Start2025PhaseNot applicableConditionsStroke, Sleep and sleep disordersParticipants62Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestSecondary6 months
  • Verbal FluencySecondary6 months
  • Clock Drawing TaskSecondary6 months
NCT06754124Start2024PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, EpilepsyParticipants30Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal FluencyPrimary8 weeks
NCT06698809Start2026PhaseNot applicableConditionsSleep and sleep disordersParticipants22Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondarysame day
  • Psychomotor Vigilance TaskSecondarysame day
NCT06553235Start2024PhaseNot applicableConditionsCancer, Sleep and sleep disordersParticipants84Lead sponsorOtherStatusRecruitingLibrary 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
NCT06471634Start2024PhaseNot applicableConditionsAging, frailty and exercise, Obesity and diabetes, Sleep and sleep disordersParticipants44Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary12 weeks
NCT06423118Start2024PhaseObservationalConditionsAging, frailty and exercise, Sleep and sleep disordersParticipants300Lead sponsorOtherStatusRecruitingLibrary tests named
  • Trail Making TestPrimarysame day
  • Verbal FluencyPrimarysame day
  • Category FluencyPrimarysame day
  • Selective Reminding TaskPrimarysame day
NCT06243172Start2024PhaseObservationalConditionsObesity and diabetes, Sleep and sleep disordersParticipants60Lead sponsorOtherStatusStatus unknownLibrary tests named
  • Trail Making TestSecondarysame day
  • Verbal LearningSecondarysame day
  • Verbal FluencySecondarysame day
  • Symbol CodingSecondarysame day
  • Letter-Number Sequencing TaskSecondarysame day
NCT06170073Start2023PhaseObservationalConditionsAging, frailty and exercise, Sleep and sleep disordersParticipants238Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningSecondarysame day
  • Verbal FluencySecondarysame day
  • Attention Network TestPrimarysame day
NCT06169254Start2023PhaseNot applicableConditionsDementia and Alzheimer's, Sleep and sleep disordersParticipants30Lead sponsorOtherStatusCompletedLibrary tests named
  • Verbal LearningSecondary12 weeks
  • Verbal FluencyPrimary12 weeks
  • Attention Network TestPrimary12 weeks
NCT06052514Start2024PhaseObservationalConditionsSleep and sleep disorders, COVID-19 and long COVIDParticipants22Lead sponsorOtherStatusCompletedLibrary tests named
  • Stroop Color-Word TestSecondary6 weeks
  • Verbal FluencySecondary6 weeks
  • Digit Span TestSecondary6 weeks
  • Symbol CodingSecondary6 weeks
  • Psychomotor Vigilance TaskSecondary6 weeks
NCT06043440Start2023PhasePhase 2ConditionsSleep and sleep disordersParticipants230Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary6 months
  • Cancellation TestSecondary6 months
  • Paired Associate LearningSecondary6 months
NCT06032715Start2023PhaseNot applicableConditionsSleep and sleep disorders, Pain and fatigueParticipants120Lead sponsorOtherStatusRecruiting

Paper 1Paper 2

Library tests named
  • Verbal FluencyOther outcome6 weeks
NCT06032377Start2023PhaseNot applicableConditionsDepression and bipolar disorder, Sleep and sleep disorders, Anxiety, PTSD and OCDParticipants275Lead sponsorOtherStatusRecruitingLibrary 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
NCT05924425Start2024PhasePhase 4ConditionsDementia and Alzheimer's, Sleep and sleep disordersParticipants62Lead sponsorOtherStatusRecruitingLibrary tests named
  • Verbal FluencySecondary9 weeks
  • Selective Reminding TaskSecondary9 weeks

Page 1 of 3

Questions, answered from the data

How many sleep trials use Verbal Fluency?

58 registered sleep and sleep disorders studies on ClinicalTrials.gov name it in an outcome measure, 20 of them in a primary outcome: 8% of the condition's 749 studies with a cognitive outcome, against 11% of all of them. It is the 7th most named test in sleep trials.

Which tests do sleep trials use with Verbal Fluency?

The Trail Making Test (24 studies), Verbal Learning (19 studies) and the Digit Span Test (18 studies).

When do sleep trials measure Verbal Fluency?

Half of the primary outcomes that name Verbal Fluency are measured within 12 weeks of the start, and the middle half from 2 weeks to 12 months. 19 primary outcomes give a duration.

How many completed sleep trials that use Verbal Fluency have reported results?

12 of the 25 completed studies that name it, 48%, have reported results: 8 posted them on ClinicalTrials.gov, 9 have a results paper linked to the registry record, and 5 did both. The other 13 show neither. Of all completed studies with a cognitive outcome, 46% have reported results.

More on Verbal Fluency and sleep and sleep disorders

  • Every cognitive test in sleep trials: 749 studies
  • Verbal Fluency in all clinical trials: 1,745 studies

Verbal Fluency in other conditions

  • Dementia and Alzheimer's248
  • Cancer200
  • Mild cognitive impairment177
  • Depression and bipolar disorder154
  • Parkinson's disease140
  • Aging, frailty and exercise136
  • Stroke110
  • Schizophrenia and psychosis107
  • Brain injury and concussion86
  • Cognitive impairment and decline63
  • Obesity and diabetes63
  • Anxiety, PTSD and OCD61
  • Cardiovascular disease61
  • Multiple sclerosis58
  • Pain and fatigue53

Other tests in sleep trials

  • Psychomotor Vigilance Task237
  • Stroop Color-Word Test89
  • Symbol Coding89
  • Trail Making Test85
  • Verbal Learning66
  • Digit Span Test63
  • N-Back Task51

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.

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