This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Melatonin for Circadian Sleep Disorders in the Blind (NCT00911053), a non-randomized na study. The primary outcome is Treatment Effects on Circadian Phase Will be Assessed During Each Trial by Measuring the Timing of Endogenous Melatonin Secretion..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00911053 |
| Phase | NA |
| Condition | Insomnia, Blindness, Daytime Sleepiness |
| Allocation | Non-Randomized |
| Design model | Factorial |
| Masking | Single |
| Enrollment | 59 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Oregon Health and Science University |
| Results posted | Yes |
2. Clinical Question
The study addressed how sleep scheduling, melatonin, and light relate to circadian rhythms in people with blindness and sleep-related concerns. The registry describes a multi-part project: identifying participants’ rhythms of sleepiness, wakefulness, and melatonin levels; exploring melatonin dose and timing; and examining light. The record also describes an optional longitudinal study for participants whose rhythms were not clearly free-running.
Population
The study concerned people with blindness and circadian sleep disorders. Insomnia and daytime sleepiness are also listed among the conditions. Detailed eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
The interventions listed are melatonin, a regular sleep schedule, and light. The project description includes several distinct phases and sub-studies, as well as optional longitudinal monitoring. The specific regimen received by each participant is not reported in the registry record.
Comparator
Baseline and several intervention or monitoring arms are listed. Allocation was nonrandomized, and the registry record cautions that the arms are not a like-for-like control comparison. A single uniform comparator is therefore not established by the record.
Primary question
The stated primary outcome was treatment effects on circadian phase, assessed by measuring the timing of endogenous melatonin secretion during each trial. No outcome measurements or treatment-effect estimates are available in the registry record.
Accordingly, the clinical question can be described from the study aims, but it cannot be answered from posted outcome data. The record reports that no study data are available after unsuccessful efforts to contact the principal investigator or study team.
3. Trial Design
The registry describes a nonrandomized study with single masking and a factorial model. Enrollment is listed as 59. The study is marked terminated, with a start date of 1997-06 and a primary completion date of 2012-06. The phase is recorded as NA. These design labels describe the registry entry; they do not provide enough detail to reconstruct how participants moved through the study or how treatments were assigned.
The project description outlines three parts and five embedded sub-studies. The first part was intended to identify individual patterns in sleepiness, wakefulness, and melatonin levels, including a sub-study on regular sleep schedules. The second part was intended to examine melatonin dose and timing, including a sub-study on melatonin metabolism. The third part introduced light, with sub-studies concerning outdoor light and artificial bright light behind the knee. An optional longitudinal study was described for participants whose rhythms were not clearly free-running.
Although the registry calls the model factorial, the factors, levels, assignment procedures, and planned contrasts are not reported in the registry record. It is therefore not possible to tell how the factorial label maps onto the five listed arms or the project’s embedded studies. The identity of the party or parties masked is also not reported.
The registry lists Baseline, Melatonin, Light, Regular Sleep Schedule, and Longitudinal Monitoring groups. It warns that the nonrandomized allocation does not create a like-for-like control comparison. The record does not report a protocol-level sample-size justification, an interim-analysis plan, or a detailed statistical analysis plan. It also states that no study data are available, so the design description cannot be matched to observed participant flow or outcome analyses.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: The PI has retired from the institution. Sincere efforts were made to contact the PI/study team members, but were unsuccessful. No study data are available.
Overall Study
| Stage | Baseline | Melatonin | Light | Regular Sleep Schedule | Longitudinal Monitoring |
|---|---|---|---|---|---|
| STARTED | 0 | 0 | 0 | 0 | 0 |
| COMPLETED | 0 | 0 | 0 | 0 | 0 |
| NOT COMPLETED | 0 | 0 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: The PI has retired from the institution. Sincere efforts were made to contact the PI/study team members, but were unsuccessful. No study data are available.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: The PI has retired from the institution. Sincere efforts were made to contact the PI/study team members, but were unsuccessful. No study data are available.
| Characteristic | Unit | Baseline | Melatonin | Light | Regular Sleep Schedule | Longitudinal Monitoring | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 0 | 0 | 0 | 0 | 0 | 0 | |
| Age, Categorical: <=18 years | — | — | — | — | — | — | |
| Age, Categorical: Between 18 and 65 years | — | — | — | — | — | — | |
| Age, Categorical: >=65 years | — | — | — | — | — | — | |
| Sex: Female, Male: Female | — | — | — | — | — | — | |
| Sex: Female, Male: Male | — | — | — | — | — | — |
6. Primary Endpoint
The registry lists the primary outcome as Treatment Effects on Circadian Phase Will be Assessed During Each Trial by Measuring the Timing of Endogenous Melatonin Secretion., measured over 1 year.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary outcome was described as treatment effects on circadian phase, assessed during each trial by measuring the timing of endogenous melatonin secretion. The timeframe is listed as 1 year. The registry does not specify a measurement unit, a summary parameter, or a dispersion measure, and no endpoint values are available.
In general, the timing of an internally produced signal can serve as a marker of circadian phase: it may indicate where a biological rhythm falls in relation to the day. Measuring endogenous melatonin timing is therefore relevant to a study concerned with sleep-wake rhythms and circadian regulation. That general rationale does not establish how the measure was collected, how phase was defined, or which change would be considered important in this study; those details are not reported in the registry record.
The primary outcome statement indicates an intention to assess the timing measure during each trial, but the record contains no observed measurements, group summaries, treatment-effect estimate, confidence interval, or statistical test. The stated timeframe alone does not reveal when each participant was assessed or how many assessments contributed to an analysis. As a result, neither the direction nor the magnitude nor the precision of any effect can be evaluated from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive point is that the registry record contains no study data. It explicitly says that no study data are available and describes unsuccessful efforts to contact the principal investigator and study team. Consequently, there is no posted estimate of change in circadian phase, no comparison between groups, and no basis for judging the size or direction of a treatment effect.
The primary outcome was intended to measure the timing of endogenous melatonin secretion. The record does not provide participant-level results or even summary statistics for that measure. Without an estimate and its uncertainty, it is not possible to assess how compatible the data would be with different possible effects. No confidence interval or p-value for the primary outcome is reported. The number of analyses is listed as 0, consistent with the absence of posted analyses, rather than evidence of a null result.
The nonrandomized allocation is important when interpreting the planned arms. Even if outcome summaries were available, differences between groups could reflect how participants entered or were assigned to those groups, as well as differences in treatment exposure. The record itself cautions that the arms are not a like-for-like control comparison. The factorial label does not resolve this concern because the factor structure, assignment approach, and planned comparisons are not described.
The registry lists 59 as enrollment, but that figure does not establish how many participants contributed data to any outcome. Participant flow, exclusions, adherence, and missing outcome measurements are not reported in the registry record. Nor are there posted results for the secondary measures of sleep, alertness, or subjective ratings. Thus, the enrollment entry should not be treated as an analysis sample size.
The adverse-event listing shows groups with zero participants at risk and zero events recorded. Because no participants are listed as at risk in those entries, those zeros cannot establish that adverse events did not occur. They indicate that the registry record does not provide an informative safety assessment.
Overall, the posted record documents study aims and design labels, not empirical findings. It cannot support a conclusion about whether the listed interventions changed circadian phase, sleep, alertness, or any other outcome, nor about the precision or reliability of such a change.
9. Statistical Methods Explained
The registry identifies the study as nonrandomized, single-masked, and factorial. These labels describe broad design features, but they do not supply the details needed to reproduce or fully evaluate the analysis. The factor definitions, assignment procedures, masking roles, outcome models, and planned contrasts are not reported in the registry record. No statistical analysis is posted, and the record states that no study data are available.
What does nonrandomized allocation imply?
In general, random allocation helps make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics at the time of assignment. In a nonrandomized study, that protection is absent. Differences between groups may reflect participant characteristics, study phase, treatment selection, or other factors in addition to the intervention. Statistical adjustment can sometimes address measured differences, but it cannot guarantee removal of confounding, particularly when relevant factors were not measured. The record does not describe an adjustment strategy, and no comparison estimates are posted.
The registry explicitly cautions that the arms are not a like-for-like control comparison. That warning limits what could be inferred from a simple contrast between a named intervention group and Baseline. It also means that arm labels alone should not be read as proof that participants were comparable or that each contrast represents an isolated treatment effect.
What does a factorial label establish?
In general, a factorial design studies multiple factors within one framework and can be used to examine effects associated with each factor, and sometimes their interaction. Interactions arise when the association with one factor depends on the level of another. Estimating these effects requires a clear description of the factors, their levels, participant allocation, and the model used. Although this registry labels the model factorial and lists melatonin, light, and a regular sleep schedule, it does not report the factor structure or analysis model. It is therefore not possible to identify which main effects or interactions were planned or estimable.
How should an endpoint estimate be interpreted?
For a quantitative outcome such as the timing of endogenous melatonin secretion, an analysis would typically summarize measurements and estimate a contrast relevant to the study question. A confidence interval describes the range of effect values reasonably compatible with the data and the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, but precision is not the same as freedom from bias. In this case, neither an estimate nor a confidence interval is reported, so precision cannot be assessed.
A p-value, when reported, measures how unusual data at least as incompatible with a specified null hypothesis would be under the statistical model, assuming that model and its assumptions are appropriate. It is not a measure of the probability that a treatment works, and it does not convey the magnitude of an effect by itself. No primary-outcome p-value is available in the registry record. It would be inappropriate to infer one from enrollment, study aims, or the absence of posted analyses.
Why can repeated measurements require special methods?
In general, repeated measurements from the same participant are correlated: observations from one person tend to be more alike than observations from different people. Analyses that treat all observations as independent can misstate uncertainty. Repeated-measures models or other approaches can account for within-person dependence, but the appropriate method depends on the measurement schedule, outcome distribution, and estimand. The project description refers to rhythms and daily monitoring for secondary outcomes, but the primary outcome analysis method and measurement schedule are not reported.
Over-dispersion is another general issue for count outcomes. It occurs when the observed variability exceeds what a simpler model assumes, which can make uncertainty estimates too small if ignored. The primary outcome is described as timing, not as a count, and no outcome distribution or model is reported. There is therefore no basis for claiming that over-dispersion was present or that a particular method was used.
What do planning illustrations mean?
In general, a sample-size calculation is a planning tool based on assumptions about an effect, variability, significance level, allocation, and analysis. It does not show that a study had a particular probability of detecting an effect after the data have been collected. The record’s planning assumptions describe an illustration based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation; the stated units differ for time-to-event outcomes and other outcomes. However, no observed primary effect or analysis is available in the registry record, and no numerical planning results are reported in the registry record of this record. Such illustrations cannot substitute for observed findings or establish the study’s original design rationale.
10. Multiplicity, Missing Data and Analysis Populations
The project includes multiple phases, five embedded sub-studies, several listed interventions, a primary outcome, and secondary outcomes. In general, testing many outcomes or contrasts increases the chance that at least one result appears notable by chance. A statistical plan may address multiplicity by defining a primary comparison, ordering tests, adjusting significance thresholds, or treating analyses as exploratory. The registry record does not report a multiplicity strategy, a hierarchy of hypotheses, or which contrasts were confirmatory.
The record names one primary outcome: treatment effects on circadian phase assessed through the timing of endogenous melatonin secretion. It also describes secondary assessments of sleep and alertness using daily diaries and wrist actigraphic monitoring, along with daily ratings of alertness and vigor. The relationship between these outcomes, the separate sub-studies, and any formal testing plan is not reported. No outcome analyses or results are available.
Missing-data handling is also not reported in the registry record. The entry does not describe the amount or pattern of missing measurements, reasons for missingness, imputation, or sensitivity analyses. It reports enrollment of 59, but does not report the number of participants with observed primary or secondary outcomes. Enrollment alone cannot establish the analysis population or the completeness of follow-up.
The registry states that the principal investigator had retired from the institution and that efforts to contact the study team were unsuccessful. It also states that no study data are available. This absence prevents assessment of participant flow, exclusions, analysis populations, and missingness. It should not be interpreted as evidence that all enrolled participants completed the study or that all planned analyses were conducted.
11. What the Result Does, and Does Not, Mean
The registry record establishes that a study was designed around circadian sleep concerns in blind people and that its project description included melatonin, light, sleep scheduling, and optional longitudinal monitoring. It also identifies a primary measure based on the timing of endogenous melatonin secretion. These registry entries describe the research aims and broad design, not the study’s findings.
The record does not provide outcome values, treatment-effect estimates, uncertainty intervals, or statistical tests. It therefore does not show whether circadian phase changed, whether any change differed across groups, or how precisely such a difference might have been estimated. The absence of posted analyses is not evidence of no effect, and it is not evidence of an effect. There is no empirical result in the registry record from which to make either inference.
Likewise, the adverse-event entries do not establish a safety result. Each group lists zero participants at risk, as well as zero events. With no participants recorded as at risk, those entries do not provide a basis for estimating event occurrence.
The nonrandomized allocation and the registry’s warning that the groups are not like-for-like would matter for interpreting any eventual group comparisons. The factorial label by itself does not establish that separate intervention effects or interactions could be isolated, because the factors and analysis plan are not described. These design constraints are distinct from the more basic limitation that no data are available.
In practical terms, this record supports a description of the intended project and its registered endpoints, but not an assessment of efficacy, harm, or clinical importance. It cannot establish whether the study completed its intended analyses, how many participants contributed outcome data, or whether observed measurements were consistent with the stated research questions. Any such conclusions would go beyond the posted record.
12. Why This Trial Matters Statistically
This study illustrates why a registered research question and an analyzable result are different things. The record gives a substantial project description, identifies a primary endpoint, and lists enrollment and design labels. Yet it states that no study data are available. Without data and analysis results, readers cannot evaluate effect magnitude, uncertainty, or the correspondence between the planned question and the eventual analysis.
It also illustrates the importance of design details when a study has multiple interventions and sub-studies. A factorial label can suggest a structure for studying multiple factors, but interpretation depends on knowing how those factors were assigned and which effects were planned. Here, the record identifies several intervention areas but does not describe the factor structure or analysis model. The nonrandomized allocation and explicit warning about unlike-for-like arms further limit causal interpretation of potential group contrasts.
The entry also shows why an enrollment figure is not equivalent to an analysis population. Enrollment is listed as 59, but participant flow and the number contributing endpoint data are not reported. Similarly, zero event entries paired with zero participants at risk cannot be treated as a safety finding. Statistical interpretation depends on denominators and outcome data, not only on recorded labels.
Finally, the record distinguishes the intended endpoint from the evidence needed to answer the research question. Timing of endogenous melatonin secretion is a stated measure of circadian phase, but no observed values or estimate is available. A transparent account of unavailable results is important: it prevents design descriptions from being mistaken for findings and makes clear which questions remain unanswered in the registry record.
13. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The most consequential limitation is that no study data are available. There are no posted primary or secondary outcome results, treatment-effect estimates, confidence intervals, or analysis outputs. The registry explains that the principal investigator had retired from the institution and that efforts to contact the study team were unsuccessful. This prevents independent assessment of the intended outcomes.
Important design and analysis details are also absent. Although allocation is labeled nonrandomized, masking single, and the model factorial, the record does not explain assignment procedures, who was masked, the factor levels, or the planned contrasts. It explicitly warns that the arms are not a like-for-like control comparison. The absence of these details prevents a clear account of how intervention effects were meant to be separated from participant or study-phase differences.
The primary endpoint is named, but its measurement unit, summary parameter, and dispersion measure are not reported. The record does not describe the exact measurement schedule or the statistical model. Although the timeframe is listed as 1 year, this alone does not establish when participants were measured or how repeated measurements were analyzed.
Participant characteristics, eligibility details, flow through the multi-part project, adherence, exclusions, and outcome missingness are not reported. Enrollment of 59 does not show how many participants contributed data to any analysis. The registry also does not report a sample-size justification, an interim-analysis plan, or a detailed statistical analysis plan. Finally, the adverse-event entries list no participants at risk, so they cannot support an informative safety assessment.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Melatonin for Circadian Sleep Disorders in the Blind — NCT00911053.
- Registry record last updated 2019-11-27; status last verified 2019-11.
- Results first posted 2019-11-27.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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17. Record Summary
The registry record identifies NCT00911053, titled Melatonin for Circadian Sleep Disorders in the Blind. Oregon Health and Science University is listed as sponsor. The study is marked terminated, with enrollment of 59, a start date of 1997-06, and a primary completion date of 2012-06. Its design is listed as nonrandomized, single-masked, and factorial, with phase recorded as NA.
The project description covers sleep and melatonin rhythms, melatonin dose and timing, light, regular sleep schedules, and optional longitudinal monitoring. The primary outcome concerns treatment effects on circadian phase, assessed through the timing of endogenous melatonin secretion, with a timeframe of 1 year. Secondary outcomes concern sleep, alertness, and subjective ratings.
No study data are available in the registry record. No outcome analyses are posted, and the record cautions that the listed arms are not a like-for-like control comparison. The information therefore describes study intentions and registered design features but does not establish clinical or statistical findings.